When a female (or male) gives there partner oral pleasure (also known as a blowjob) until they orgasm. He/she holds the semen in there mouth spits it onto the scrotum and rubs it around the testicles, the partner continues to drag there testicles across the others face.
Oily Sax
"Dude I so totally Oily saxed my wife last night!"
"Aye girl, wanna do an Oily Sax?"
Bro #1- "I got kicked in my nads last night."
Bro #2- "why man?"
Bro #1- "I told my Girlfriend I was going to oily sax the fuck out of her"