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2.
–noun
(slap-bak)

Both an auditory and tactile phenomena that occurs whilst performing coitus in the rear penetration position (doggy-style). Exacerbated by low light conditions and intoxication. It makes one aware, that regardless of intention, they are engaged in intercourse with an individual possessing male sexual organs.
Awww, man. I was so fucked last night. I took that tall chick home and I just didn't realise till' I felt some slapback. FUCK!
by MajorBlue October 24, 2010
 
1.
the rating of which the ability to smack a big ass with one hand on one cheek and feel and catch the vibration on the other cheek with the your other hand. Ultimately the best asses should be able to send the vibration back to the hand that originated the slap. These happen to be the best booties for slap back.
Damn son! You know that Ashleigh got that slap back for real.
by Douggie Fresh March 18, 2008
 
3.
A turd so long, that it sticks out of the water and could literally slap you in the butt cheek
"Hey Javier, I just took a shit so big it almost gave me a slapback!"
by Javier4life November 22, 2013