to smile out of happiness while crying of sadness
she had lost all hope, but love in friendship made her dawn a rainbow smile
ayon kay audiodecoy ika-04 ng Abril, 2005
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!
ayon kay El Chin Chon ika-06 ng Pebrero, 2009