Chalk this up to the dangers of live television.
>> LIVE UPDATES: Follow along as the parade makes its way through Philadelphia
Kelce, who has spent his entire seven-year NFL career with the Eagles, enthusiastically joined in, forcing 6ABC to cut away quickly when the two-time Pro Bowler began tossing out the song's customary f-bombs.
Watch (warning: explicit language):
Kelce was also spotted making his way up the parade route on a police officer's bicycle and chugging a beer, all within the first few minutes of the start of the parade.
"I'm having a blast, brother!" Kelce said.
Kelce's verbal snafu wasn't the only profane moment caught on live television. Prior to the start of the parade, NFL Network host Kyle Brandt (beloved by Birds fans for his passionate defense of the Eagles) asked a fan to say one nice thing about the Cowboys.
Predictably, the conversation didn't go well.