Omo means Child in the Yoruba language. It is used to refer to a child, a person regardless of age in contexts or child of- a concept or Identity. It can be used for exclamation as well.
omo can be used short to stand for Omorashi Omorashi is a Japanese word that means 'to wet yourself'
Omorashi is a sexual fetish that involves peeing on yourself or peeing on someone else, and holding your bladder.
(Watersports is the same as Omorashi, but is the English version)
(slacker friend): "dude, totally just got the over achiever as my partner for the history project."
(you): "yeah there wasn't anyone left in my class so looks like I am OMO again..."
Or
(you): "dude Chelsea just asked duke to the dance!"
(best friend): "that sucks! Guess your goin OMO again."