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1.
A male who steals another man's wife and marries her. Often pick the wife up with a cheesy pick up line. Often resides in northeast.
A Keith: Are you from Tennessee

Another Man's Wife: no

A Keith: Your the only ten I see.

Another Man's Wife: Awe I'm going to leave my husband and marry you.

A Keith: Swing a dee dee.
by swizle7 May 22, 2010
 
2.
1. A Keith is when a person is being very gay about something or to someone.

2. A Keith is also used to describe someone that is singing with extreme intensity.
1. "Dude you are being such A Keith stop hogging all the guacamole."

2. Person 1:"did you see Sing Star last night?"
Person 2:"Yea, that Donald guy was A Keith on that Madonna song"
by TM1CA15 March 22, 2009