Where one tries to force a song (usually an annoying one) into someone else's head by singing, saying or humming a recognisable part.

Not really today, but over the years we've developed what's called a "song slap".

You only need a really annoying song that everyone knows (usually from the 80s) and a friend. At random points throughout the day, start singing the song. If you hear "Damn you. Now you got that song stuck in my head" You have won.