When you smear cookie crumbs / cookie dough all over your bulging cock and either stroke it or put it in your best homie.
“Damn, I just had the best cookie rub session of my life, my homie loved his hole being filled with cookie dough.
It's when two men, typically Rico and Fang, coordinate a time and place to rub their butt cheeks together and say "COOKIES!"
Did you say you were going to go cookie rubbing with Joey tomorrow night? Sign me up!