Slabbing
The art of repeatably 'slabbing' ones nut sack and/or strap on device against the preferred orifice(s)* during a sexual encounter.

*where orifice is defined as any surface, whether socially acceptable or not.
Bloke 1 (to mate on the subject of porn): Slabbing hell, did you see the slab on that!

Bloke 2 (in response): I'd slab that!