(yuh-mil-boe) in excitement. like the word yay! with great joy. or congratulations. positive.
one
Courtney: Chris just asked me out!
Hannah: Umilbo! (congrats, or yay)

two
Courtney: Umilbo! (yay) No school today
Hannah: Umilbo! (positive, excited)
by JoMar Joritess June 11, 2008
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