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1.
to hit hard and percise. Usualy producing a THWACK sound.
With a "THWACK" the bamboo rod hit table.
by Myoga1 February 24, 2004
 
2.
To receive a hand job or blow job, and to not finish.
"Dude, she was thwacking me for an hour yesterday."
"How did you not finish bro?
by Dan GleeSack December 06, 2012
 
3.
to hit
Nikki thwacked her friend on the arm.
*thwacks you
by ^_^ September 28, 2003
 
4.
To firmly slap ones penis across another persons face i.e. to be either very manly or very homosexual.
"Dude! That little limp wristed faggot just thwacked me!"

One jock buddy says to another...
"WHOA! Billy's asleep, someone thwack him!"
by Steven Spears April 14, 2005
 
5.
The sound made by the scrotum striking the belly of a women whilst making love doggy-style
The thwack sound echoed through the room as I reached satiation.
by Hayers111 February 25, 2007
 
6.
Being under the influence of methamphetemines, particularly Ice.
My homie Dropkick left his dope on the coffee table....and his coffe table out in the yard because he was thwacked
by Sidekick Jones September 03, 2003
 
7.
A firm thumb that a hard penis gives to a female (or male... depending on your taste), in any number of places.
Puedes THWACK tu SCHLONG en mi cara, por favor?
Translation: Can you THWACK your SCHLONG in my face, please?
by Nicka-Licka-Dicka March 03, 2005