spycatching 

the act of spying on or viewing people as they are hooking up, a person that participates in spycatching is known as a spycatcher

we were spycatching on tim and jackie as they were in the bedroom

spycatching by thekid01003 February 3, 2010

Splatching 

The noise the penis makes when one starts masturbating but his penis is not entirely hard yet.

Joe started to jerk, but he got turned off by the splatching.

Splatching by Fhowa May 31, 2016