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1.
When a girl gets hit in the chin by a guy's balls while she's giving him a blowjob.
Bryan gave Dorothy a chin buster last night.
by Sasquatch Jones September 12, 2006
 
2.
when you are getting a good blow job and the female slams the males cock into her mouth too far bouncing his balls off her chin causing them both pain.
pam was blowing jon when she suddenly deepthroated it slamming his balls against her chin, causing a chin buster.
by ericbobo September 21, 2006