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1.
Something that does not fit in with a group, database, or situation.

Something that doesn't make sense.
"This spreadsheet is out-of-whack. Those entries don't make sense and don't belong there"

"There's something out-of-whack 'bout the people at this party...I'm outta here"
by Prof XXX January 01, 2004
 
2.
One who has exhausted all desire to masturbate. In this definition whack refers to semen. "Out of" suggests you are tapped dry.
Ha ha Jimmy can't play soggy cracker tonight as he is out of whack!
by zappa2001 September 04, 2005