Editor's note: This is the second installment in Bleacher Report's series on NFL urban legends. Part 1 looked at Bo Jackson's hard-to-believe 40-yard-dash time.

The 1970s Raiders were mythologized in their own time as rowdy bikers who studied their playbooks by the jukebox light on Saturday night and did everything short of bringing loaded weapons on the field on Sunday afternoon. Nearly 40 years after their heyday, it's hard to sift the facts from the purple storytelling. 

What's certain is that there was no love lost between those Raiders and their many rivals, most of whom suspected that there wasn't a rule in the book that Al Davis' team would not bend. Even Ray Guy, the NFL's first superstar specialist punter and a straight man in the Raiders circus, wasn't above suspicion.

When Guy's booming punts caught another legendarily wacky 1970s team by surprise, hijinks—and an Urban Legend—ensued.

The legend: Ray Guy used a helium-filled football against the Oilers in 1977, prompting an early Deflategate not long after Watergate made every scandal a "-gate."

What we know: This old saw came back to life recently thanks to Deflategate and earlier Guy's 2014 selection to the Pro Football Hall of Fame.

The Helium Punt certainly boasts a colorful cast of characters. Raiders coach John Madden has the most successful video game franchise in history named after him (and also was an incredible football coach). Oilers coach Bum Phillips has a freakin' opera named after him. Guy was and "is probably the finest punter in the history of the world," according to a 1977 Los Angeles Times article that still holds up. Returner Billy "White Shoes" Johnson was an end-zone dance pioneer who also caught one of the most famous Hail Mary passes in NFL history. And let's not forget Al Davis, who said of Guy in that 1977 article: "It happens in everything. Sandy Koufax had it. Muhammad Ali had it. O.J. Simpson. Elizabeth Taylor. They were born with it—the rest of us have to work for it."

(Not to digress, but Davis was born with it too, baby.)

The Raiders beat the Oilers 34-29 on November 13, 1977. Guy punted three times for an average of just 35.7 yards. He also kicked off seven times in the game. Johnson managed to return just one kickoff and one punt. Guy, Johnson and Phillips had clashed before—Johnson returned just one of Guy's nine moonshot punts in 1976—but the Oilers were extra suspicious during that November meeting.

"I have never seen anybody hang kickoffs like Guy did," Johnson told reporters after the game. "I told (special teams coach) Andy Bourgeois that the ball was hanging up there too long."

There were other suspicious details: The Raiders demanded a new ball before each punt, sometimes delaying the game to get one. Equipment manager Greg Doremus grabbed two footballs, one from Johnson when he ran out of bounds after a punt return, the other from defender Zeke Moore after an interception return. The Guy football was "slightly discolored." Doremus said in newspaper reports that Raiders representatives pushed to have the Guy ball back, but Doremus kept it.

"There's probably nothing to it," Phillips said, "but we're going to send the ball to Rice University to have it tested."

Madden quickly responded, calling the story "ridiculous."

"The officials control the balls," he said in another UPI story. "They have 24 of them in their locker room before the game, and they inflate them to the prescribed pressure."

A Raiders team assistant added that "when the officials get the balls, they aren't even out of the box or the cellophane yet."

While Phillips sent the footballs to the lab, KMPC radio in Los Angeles stopped traffic on Sunset Boulevard so their morning disc jockeys could punt helium footballs and compare them to air-filled footballs. The Raiders were still in Oakland at the time, and sports-talk radio had not yet been invented, so the KMPC stunt reveals how big a story the Helium Ball must have been for a few days in 1977.

The morning jocks determined that the helium balls traveled further than regular balls, at least when kicked by radio hosts who have no idea how to punt and a vested interest in an interesting result. More importantly, the morning jocks called the NFL and learned that there was no rule against filling a football with helium, because then (as six months ago) the NFL did not focus insane amounts of attention on inflation techniques.

By the Tuesday after the game, AP and Houston Post reports listed credible sources stating that lab tests proved negative.

"It's a big joke," Phillips said during his midweek press conference. He later apologized to the Raiders. When the Los Angeles Times profiled Guy in a nationally syndicated story in early December, the helium incident was brushed off in a few paragraphs.

In 2009, television's Mythbusters determined that a helium-filled football does not fly further or higher than a regular football. The decreased mass of the lighter football lowers force and wind resistance, negating the advantage of the less-dense gas. It's similar in principle to kicking a beach ball: lightness is not much of an advantage when trying to cut through the wind.

We can only hope Adam Savage and Jamie Hyneman are experimenting with pressure gauges and footballs in freezers as we speak. The similarities between Deflategate and Helium Ball are downright spooky, from the big picture (a successful team with a rule-bending reputation gets implicated) to the little picture (an interception return ball is confiscated as evidence). All that's missing is a Raiders equipment manager nicknaming himself "Squeaky," which, er, wouldn't have been a popular choice in the mid-1970s.

The Guy ball was not filled with helium; Phillips knew his way around a flamboyant press conference and would not let something like that slide. With his sense of humor and flair for theatrics, ol' Bum might well have just been needling the Raiders.

There's also a chance that Guy's footballs had been scuffed down, as was often the practice before the NFL introduced K-balls in 1999. That would explain slight discoloration, an urgency to get fresh footballs on the field for Guy and the Raiders' effort to retrieve the ball. Again, the NFL didn't really focus on such matters until mid-January, when they became the most important matters in the world.

While the Guy story was still current in 1977, Rams kicking coach Ben Agajanian told Rich Roberts of the Long Beach Independent a story of playing for the semipro Hollywood Bears in 1944. The team's owner decided to put helium in the footballs so the opposing quarterback would overthrow his receivers. "It seemed to work," Agajanian recalled. "The ball would just float." Agajanian kicked three long field goals to win the game. "I didn't know about the helium," he said. "I thought I was really good."

That might seem to add credibility to the Guy legend, but there are some problems with Agajanian's story. Both teams used the helium footballs? How would that have given the Bears an advantage? Sounds like a forgotten urban legend, passed along (as they usually are) by folks with confabulated memories.

If we are going back that far for legends, there is no sense searching for the Hollywood Bears. The Chicago Bears have a much more interesting legend lurking in their past. Stay tuned for that in our next installment in the Urban Legends series, which tells the strange story of the NFL's first 1,000-yard rusher, a guy you have never heard of, and who may not have rushed for 1,000 yards.

Mike Tanier covers the NFL for Bleacher Report. Reports referenced in the series were accessed through NewsLibrary.com, Newspapers.com and NewspaperArchive.com. Links to those sources have been provided where possible.