When someone comes up with some concept, like say "We all hate this specific person" and that convinces others to jump in as well and hate this specific person. This is called Jumping onto the bandwagon.
It's like a band see, some guys learn some good songs, get together and start playing, they go touring (stuffting all over the place), then they realise they hate each other and break up. It's also synonymous to marriage except with more people involved.
