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1.
When somebody says something really stupid,OMG ISS is what you should reply with. It stands for OH MY GOD. I'M SO SURE!
Drunk guy at the bar "Will you pleeaaasse take me home with you?"
Michelle "OMG ISS!"
by Sosure March 24, 2010
 
2.
Chatroom shorthand for, "oh my god I'm so sorry."
Leah: My boyfriend dumped me.
Bruce: OMGISS!
pronounciation: o-m-g-i-s-s (or just omgiss)
derivative: omg, omfug
by rosekiss February 06, 2009