What is Thwacking?

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?

Thwacking - meme gif

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.

to thwackit is to jackoff, spank the monkey, flonk the dolphin, rope the poney, wrestle with the snake, choke the chicken etc. etc.

jimmy thwacked it all night until his shlong turned chrimsen.

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!"

Nikki thwacked her friend on the arm.
*thwacks you

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?

to be speed up as much as possible off of speed/meth

lets get all thwacked out, go to the titty bar and rub tuna on ourselfs then go home to our women...

Jack: i have reverse card try and beat me bob
Bob: (thinking emoji) Thwack

to hit hard and percise. Usualy producing a THWACK sound.

With a "THWACK" the bamboo rod hit table.

I was rolling up my leather belt and it was thwacking on my pussy