> There's nothing stopping fans belting out the chorus of Delilah.

If they did during the match, the broadcasters managed to filter it out from the broadcast. But the fans not being heard singing the song in question might have had more to do with Ireland getting an early lead.

Oh, and if you want something offensive which people still sing out loud without thinking, check where "Hear him whip the women just around midnight" comes from, and ponder the meaning of that song's title.