It was not the first time the badger has been in hot water this season. He recently riled Chelsea boss Avram Grant by giving him a hug.
Billy told fulhamfc.com: "I apologise to Mr Foy. I'm remorseful of my impromptu antics at the Villa game but badgers are hard of hearing and short of sight. Had I known that he was about to blow his whistle, I wouldn't have begun the break-dance routine.
"At the Chelsea game, I just wanted to cheer Avram up as he looked miserable after the first half, although my boss wasn't sure it did the trick."
Billy has not been censured by the club and will travel to Middlesbrough for Saturday's Premier League clash.