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2.
A difficult task or someone who is difficult to persuade.
He's still not convinced although I tried my best to persuade him. Such a numb bum!
by sinthya April 30, 2006
 
1.
This is what happens to a person's rear end after sitting for too long.
That movie was so long that I ended up with a major case of numb bum.
by Libertine September 04, 2009