look up any word, like smh:
 
1.
A heavy gauge metal lock used primarily for securing bicycles. The U-lock gets it's name from a 'U' shaped metal rod that has cutouts at each end to fit into a horizontal locking bar. This is considered to be one of the best bicycle locks.
My bike U-lock is heavy, but at least my bike won't get stolen.
by Falkon November 06, 2006
 
2.
device used for breaking the jaw bones of motorists who think it is humorous to be inconsiderate and endanger the lives of cyclists on the road.

the act of breaking the jaw bone of a motorist, or perhaps smashing out his window.
safety first: always bring your u-lock.

yo, you shoulda seen the way Tido u-lock'd this dumbo's face right off!
by the.scumlife September 11, 2010
 
3.
The practice of inserting a double ended dildo into the ass hole and pussy at the same time, forming a U shape.
We were at the bachelor's party and I U locked the stripper!
by Penelope Clearwater June 10, 2008