Try this in high school or at the mall, and you'd have an all-out brawl.
"It's legal. It is a body part, like someone's arm or leg," NFL head of officials Mike Pereira said.
Hmmm, turns out the most dreaded tackle when Pittsburgh and Arizona meet Sunday may not be one of those teeth-jarring, helmet-to-helmet hits. By a hair, it might be the prospect of seeing a player taken down by his tresses.
Want proof? Search YouTube for "Polamalu" and "hair" and "tackle," and watch the first thing that appears. There's a 27-second clip from 2006 of the Steelers star being ripped to the ground by his free-flowing locks after an interception.
"I was so disturbed by it," Hollywood stylist Michael Shaun Corby said after watching it Thursday. "But I probably watched it 50 times. I'm going to put it on my MySpace page right now."
"I think a little pulling of the follicles is good, it gets the blood going," he said. "But I'd say it's never a good thing to have your hair pulled by a 300- or 400-pound man."
Having styled for Paris Hilton, Lindsay Lohan and other celebrities, Corby offered some advice.
"The main thing is extra protein. That gives you strong hair. And the richest source of protein is hemp. I would tell those players to get more hemp into their system," he said. "I'm sure the NFL won't appreciate me saying that."
Oh, Corby made one other observation.
"Whatever happened to the days when pulling someone's hair was just wrong?" he said. "Little girls do that. It's so unmanly, right?"
Hardly something Johnny Unitas and Ray Nitschke worried about. Johnny U wore a crew cut into the Hall of Fame, Nitschke was bald when he led Green Bay to victory in the very first Super Bowl.
Whatever, Fitzgerald and Polamalu are fair game if they're carrying the ball. Certainly gives new meaning to helmet hair, too.
Polamalu's black mop hangs a few inches past his shoulders. The Steelers' safety hasn't cut his hair since 2000 to salute his heritage and the Samoan warrior spirit.
"It's kind of become an extra appendage to me," he said. "Sometimes I do wish I could go without it, just out and about with my wife. It's kind of a dead giveaway."
Fitzgerald's neatly woven dreadlocks drape down even farther. His mom wore hers the same way. She died in 2003 from breast cancer, and the Cardinals' record-setting receiver hasn't had a haircut since.
"I grow it as a tribute to her, in her honor," he said. "So every day I look at myself in the mirror and I think about her and what she means to me."
Last spring, the NFL briefly toyed with making a rule requiring players to curb their long hair. It clarified its rule in 2003 when Ricky Williams was tackled by his dreadlocks. He later trimmed his hair, as did Cardinals running back Edgerrin James after he was a similar victim.
"If you were going to wear it long, you were subject to getting pulled down," Pereira said.
Fitzgerald said it hasn't happened to him yet. Polamalu was nailed by Kansas City's Larry Johnson two seasons ago, and the YouTube video had been seen more than 600,000 times.
Johnson stuck out his right hand and tugged Polamalu, sending him toppling. The Chiefs' rugged running back never let go -- he was penalized 15 yards when he hoisted Polamalu back onto his feet by his hair.
"No, it didn't hurt," Polamalu said.
Steelers offensive lineman Tony Hills figures he's watched that clip 1,000 times. "I cringe a little bit every time. That's a man's head."
Arizona lineman Elliot Vallejo sounded eager to try that tackle.
"If I can make a play, that's the first thing I'm reaching for," he said. "Along with being mean and obnoxious, you know if you grab that as a handle, he's going down."