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1.
Just another name for a mental hospital.
"What the hell? Ron's been acting like he's straight out of the looney bin."
by BodyBreaks November 19, 2008
 
2.
Noun
1. A place to house the mentally disabled.
2. One who resides in a loonybin, or acts like it.
There's loonybins in that loonybin
by Andre January 07, 2004
 
3.
a state of mind that is achieved once one has taken in a large amount of THC, the main ingredient in marijuana. The looney bin can be reached when a person feels "retarded" and unable to function normally.
Five bong tokes later and I was in the looney bin.
by Kelsmaster Flex June 17, 2008