a paddywhack is like when you feel like you think about it a lot and you need to know what its like, but it also encompasses a preference for larger partners in general.
"dude you talk about these fat ladies a lot you sound like you need a paddywhack"
"girl i know he was big but he was a solid paddywhack"
The act of someone grabbing your dick tight, and then slapping the hell out of your balls until you cum. this can be done in several ways, such as the self Paddywhack, and the suspended Paddywhack, where you are suspended uside down and whacked.
that irish girl was crazy last night. my balls are still sore from that Paddywhack.
i gave myself a Paddywhack yesterday because my girlfriend is out of town.