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2.
when something is all gone
the milk in the glass is now ubos.
by Freediver May 10, 2005
 
1.
Unhealthy Boy Obsession Syndrome

When you just happen to know everything about a boy that there is to know. Their address, their age, hobbies, grades, personality, what their house looks like on the inside, their families names, you stalk their social networking sites to the point where they will find out eventually even if there is no legitimate evidence you were on their page.

Some results of this could be bad like them thinking you are a creepy stalker, or a freak that will never get a boyfriend.
Girl: "Man, I've got such a bad case of UBOS, he's so gorgeous!"

Boy: "Holy shit take that UBOS to some other guy you freak!"
by CanOfBread February 27, 2011
 
3.
Useless Bag of Skin zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
Andy was a UBOS.
A loser. A worthless person.
by Frankie Alvert February 07, 2005