It's where your wife keeps your balls once you get married.
My wife keeps a lock on the ball jar to keep me in line.

My wife always keeps a lock on the ball jar, but opens up the dick jar once a year so we can have sex.
by -hef- September 16, 2009
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to be completely and utterly whipped by the female girlfriend.
Spencer, are your balls in a jar on your girlfriends desk? Why don't you get them out and chug that there beer.
by Cac2490 March 21, 2012
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