An amazingly tight, big ass. In relation to the popping sound it would make to during doggy-style or the way a quarter would bounce off of it.

smash factor is originated from a ratio in which a ball bounces off the surface.
"Damn fool, check out the smash factor on her."

"Dude, this girl last night had a NICE smash factor."
by mpimp00gf June 30, 2009
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