A euphemism for throwing up.
Dude, this kid in my class got sick and totally rainbow smiled alllll over the room. He couldn't even make it to the bathroom!
di El Chin Chon 06 febbraio 2009
to smile out of happiness while crying of sadness
she had lost all hope, but love in friendship made her dawn a rainbow smile
di audiodecoy 04 aprile 2005