Nut sack crack is the crevice between the testicles created from placing your finger in between them.
Joey: Hey, Jim, come check out this nut sack crack.
Jim: Oh wow, dude, that's some nice sack crack!
Joey: Thanks, man, I work out.
Jim: Oh wow, dude, that's some nice sack crack!
Joey: Thanks, man, I work out.
by Psicotik May 29, 2012