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1.
The opposite of a green thumb; a person who doesn't know his brass from his oboe about taking care of plants.
Who are you giving that tree to? I wouldn't trust Lana. She's a brown thumb. You give her any plant, it'll be dead in one day!
by pentozali December 20, 2007
 
2.
The act of waking up early, dropping the dugan of your life, and then frantically wiping to complete the experience; unfortunately when wiping the excess remains on your thumb.
Dude, I passed the most amazing BM that there was nothing that I could do to avoid the Brown Thumb.

(calling best friend) {You} You would not believe what happened this morning. {Friend} I cant talk. {You} It involves the brown thumb. {Friend} I've got time for that. Tell me more.
by +8 January 08, 2009
 
3.
A person who enjoys sticking their thumb in peoples bum and sometimes the brown thumbs own bum.
Don't shake hands with a Jackie they're brown thumbs.
by one thumbs up August 21, 2010