Nothing, zero, zilch, nada, shit all. Possibly a short, fat man.
"I came out of that deal with jack squat."
"Here comes that prick, Jack Squat."
by chico del nacho September 20, 2003
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Nothing. Identical in meaning to jack shit - it's just an equivalent for people who are scared of profanities.
Your car's worth jack squat.
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A stronger variation on the slang usage of "squat", meaning "absolutely nothing".

The origin of the phrase is unknown, but most likely it shares roots with the negatory slang usage of "jack".
"I get paid jack squat at my job."
by _Fabricated_ September 21, 2003
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a polite way to say 'jack shit' meaning
nothing of value or worth
Front You some weed?
Dude, You ain't got jack squat to pay me with. Ya moochie assed cunt.
by Mr.Skullhead September 20, 2003
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