Dungy, a former defensive coordinator and assistant coach with the Vikings, said he saw plenty of Packers fans' butts during his yearly trips to Green Bay.
"Anyone who has played in the NFC Central knows what that's about," Dungy said Monday at a news conference in Indianapolis. "It's not the kind of thing you want to see on national TV, but I understand what it was all about.
"The fans in Green Bay have a tradition in the parking lot after the game where they moon the visiting team's bus. It's kind of a unique send-off.
"I had seen it seven times because when I was with the Vikings, we lost to them seven times up there," he said.
Vikings players found Moss's antics, which came after a 34-yard, game-clinching touchdown, humorous. Whether the NFL will see the humor is unlikely. The league is reviewing the incident and likely will fine Moss later in the week. The league prohibits "obscene gestures or other actions construed as being in poor taste."
When Denver quarterback Jake Plummer exposed his middle finger toward a heckling crowd earlier in the season, it cost him $5,000. With Moss having a bigger NFL rap sheet — including a $25,000 fine for squirting water at an official in 1999 — his fine likely will be costlier than Plummer's.
Moss refused to shed much light on his celebration after Sunday's game, telling reporters in the locker room: "What I did was just play a little bit. I wasn't trying to be mean or anything like that. It's just a celebration. That's all. Nothing big."
In an on-field interview conducted by Fox moments after the game, Moss said: "Just having a little fun with the boys. I hope I don't get in trouble by it, but if I do I'll take the heat."
Moss would not comment on the incident Monday.
His teammates and coach Mike Tice did have something to say, though.
Tice, who called the Packers' fans "classy" during a conference call with Wisconsin media earlier in the week, wasn't quite as kind on Monday.
"I always felt that Green Bay fans had a tremendous amount of class," Tice said. "I didn't see that displayed particularly often yesterday, and some of the things I heard was unlike Green Bay fans. Maybe they weren't the normal season-ticket holders."
"You should have heard some of the things they said to him on the sideline," tight end Jermaine Wiggins added. "They said a lot of bad things, things you shouldn't say to people."
Wiggins said the incident has been blown out of proportion because of Moss's reputation.
"The guy's having a good time. He's having fun. That's great. People shouldn't take it to heart," Wiggins said. "But it's Randy Moss, so people have to make a big deal out of it. If it was anybody else, it would be water under the bridge."
Moss's image took a hit last week when he walked off the field with 2 seconds remaining in the regular-season finale at Washington. That reputation contrasts with what Moss usually does after scoring a touchdown in Minnesota, where he hands the ball to a child sitting in the handicapped section.