NFL fans are a curious lot. They will often be loyal even when their teams are in the midst of a massive collapse (for the Cleveland Browns, that would be roughly the past 20 years).

But they can also be fickle, with the boos beginning to echo through the stadiums at the first sign of poor play.

This slideshow, however, isn't going to be dedicated to the iterations of fandom, which can be filled with the ecstasy of victory or with the absolute dejection of defeat.

Instead, it will focus on the meanies of the NFL world. These fans will yell expletives at the first sight of a rival's jersey. They'll flash the bird at referees before they even see a replay. And yes, they'll even pelt old Saint Nick with snowballs when he dares to try to bring some Christmas cheer to the stadium.

These, my friends, are the meanest fans in the NFL.

10. Seattle Seahawks

Although Seattle is typically better known for its fantastic coffee and rainy skies, Seahawks fans have gotten the reputation for being loud and rambunctious.

The Pacific Northwest is a fairly laid-back place on the whole, but on game day at the stadium formerly known as Qwest Field (now CenturyLink Field), the fans can be a bit high-strung.

With the Supersonics jetted out of town and the Mariners continuing their decade-long quest for baseball futility, the Seahawks are the best game in Washington State these days.

Opposing teams frequently mention how loud and raucous Seattle can be. Seahawks home games feature more false starts from opposing teams' offenses than any other team in the NFL at 2.36 on average per game.

Seahawks fans have made CenturyLink Field an exceedingly difficult place to play.

9. Baltimore Ravens

Baltimore Ravens fans are a notoriously cantankerous bunch. While they're fairly equal opportunity in their hatred of other teams' fans, they do reserve special vitriol for fans of the Indianapolis Colts. Check out this YouTube video of Baltimore Ravens fans heckling Colts fans.

The team itself even reserves the right to malign the Colts for their long-ago betrayal of their city in the dark of night. When the Indianapolis Colts visit Baltimore, they appear on the scoreboard as merely "Indy." The name "Colts" doesn't appear anywhere in the stadium.

Bob Irsay and his Mayflower trucks are still reviled like nothing else in the city's history. Baltimore fans still hold a grudge against the current iteration of the Colts, although 1984 was almost 30 years ago and Bob Irsay is long gone.

If that's not mean, I don't know what is.

8. Detroit Lions

Lions fans haven't had a lot to celebrate over in the team's history, and as a result, they're a hostile bunch.

Detroit Lions fans reflect their city's gritty Rust Belt ethos. They are a relentless pack of Midwesterners spoiling for a fight.

In fact, they are so mean that they even excoriated the team for hiring Nickelback to perform at halftime on Thanksgiving this past season.

Well, maybe they had a point there. Nickelback is the most milquetoast "rock" band this side of Blink 182, but they still get points in the mean column for their hatred of the Chad Kroeger-helmed Canadian rock group.

7. Dallas Cowboys

The insufferable moniker "America's Team" is only the beginning of the wretchedness of Dallas Cowboys fandom. Texas is the state, after all, that gave us the most arrogant catch phrase in the history of interstate rivalries: "Everything is bigger in Texas."

Everything may be bigger, but everything is certainly not better. That is especially true when your team is led by a mediocre quarterback and an under-performing defense.

The Cowboys are a team that has the talent to be great, but haven't tapped into it recently like they should. As such, Cowboys fans have had to be fueled by their past greatness (which occurred when Vanilla Ice was still relevant in the pop world) and the obscene massiveness of their new stadium and out-sized Jumbotron.

All of this underachieving and misplaced hubris has made the denizens of Dallas mean. They have earned their sixth-place finish on the list of top-10 mean fanbases.

6. New England

Boston has a reputation for being rife with rude and inconsiderate fans. When these folks descend on Foxborough to cheer on their Patriots, they become the essence of mean.

To make my point, here is an unlikely story about nice Patriots fans. In it, Peyton Manning comments at length about a group of New Englanders who treated him with respect and kindness. The fact that this is taken as news is proof enough that the majority of Pats fans are ornery and contrary.

Another beef with Patriots fans has been their fair-weathered nature. Prior to Tom Brady's ascendancy in 2001, New England fans had very little to cheer about. Now that they have a decent team, they are suddenly hopping around like they've loved the team since they were babies in diapers.

Their insecurity and the sense that all of their hard-won respectability could vanish at any time breeds a distinct and unsavory meanness in their nature.

5. New York Giants

Have you seen the "license plate guy?" Most of you first saw him featured on Monday Night Football in the Superdome.

Instead of the swamps of Jersey, Giants fans tend to make their way down to MetLife Stadium via NYC or Upstate NY.

Hard-bitten New York Giants fans are a tough crew. They love their team and despise their opponents. They also despise their former players, apparently.

This video shows Giants fans booing their former star running back, Tiki Barber, as he's inducted into the team's Ring of Honor. This is all the proof you need to understand the unplumbed meanness in the souls of Giants fans.

4. Pittsburgh Steelers

The Steelers' faithful travel well and seem to be located throughout entire country.

Pittsburgh fans love their team and hate everyone else. Not only do they have a fiery-hot hatred of other teams, but they fan the flames of that hatred with their truly terrible yellow towels.

Of course, any article written in the home of the division rival Baltimore Ravens' newspaper should be taken with a heaping tablespoon of salt, but this piece in the Baltimore Sun highlights a typically mean Steelers fan archetype.

The Steelers have a huge national fanbase. Their mouthy fans find their way to all sorts of road games—from Jacksonville to San Diego and everywhere in between.

3. New York Jets

This team has its own enforcer (Fireman Ed)!

Jets fans—like all New Yorkers—are loud, and they are proud. So don't ever enter MetLife Stadium and talk about their accent or how greasy their hair is.

New York Jets fans mimic their brash head coach Rex Ryan. They talk a great game, but of late, can rarely back up their bold trash talk with results on the field.

Any fanbase that calls themselves a gang (as in "Gang Green") have to have a mean streak. This year, their mean behavior manifested itself as a vociferous hatred for ineffective starting quarterback Mark Sanchez.

This is group of fans that you don't want on your bad side when you enter MetLife Stadium.

2. Oakland Raiders

No visiting team enjoys stepping into The Black Hole.

Since the 1970s, the Raiders have relished the role of NFL villains. Just like their misfit team, Raiders fans wallow in the glory of being bad boys.

I've taken a light-hearted approach to most of these slides, but the shootings after a Raiders preseason game earlier this year is no joke. The thuggish behavior often on display in Oakland escalated into a nasty incident this past August and caused many to question if boorish fan behavior had gotten out of control in the Bay Cities.

Bleacher Report's Elias Trejo wrote this piece early last year about how the fear of ruffians at the games has actually hurt Raiders home game attendance.

Raiders fans are certainly passionate, but perhaps they need to chill out a bit in the interest of gaining a more wholesome reputation.

1. Philadelphia Eagles

Eagles fans have to top this list. They cheered when Dallas Cowboys receiver Michael Irvin hit the turf with an injury in 1999, and they booed Donovan McNabb out of town. Perhaps most notoriously, they pelted a genial dude dressed in a Santa Claus outfit with snowballs in 1968.

Lincoln Financial Field has long been known as a rough-and-tumble place. These fans are vituperative to the point of obnoxiousness.

Philadelphia is a blue-collar place that breeds a strong sense of identity. Their fans wear that identity on their sleeves and manifest it as emotional and mean to the extreme.