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1.
umg
An exclamation of amazement and disbelief.
umg I just won the lottery!
by Zaul September 23, 2003
 
2.
umg
Alternative spelling of "omg", carries the same meaning. Read as "Uh mah gahd" or "Ooooh my god".
umg look at my new hat!!!
by jorbs October 18, 2014