Every party needs a pooper, that's why we invited you
Party Pooper, Party Pooper

One sings this song when a friend won't go along with an idea or activity, and one wants to pressure them into it. (A humurous way to shame, guilt, and persecute.)

This song is a spoof of off the 1916 song "Pretty Baby" by Gus Kahn, Tony Jackson, and Egbert Van Alstyne. The lyrics of the original are as follows:

Everybody loves a baby, that's why I'm in love with you,
Pretty baby, pretty baby.