Acronym; standing for; Cum on your face. Can be used also by replacing 'Y' for 'H', Cum on her face. To be used in public places where it may not be appropriate to say "cum
on your face."
What I wouldn't give to coyf.
I was walking in the mall yesterday and I saw a girl. After approaching her I politely asked; "excuse me miss, would you mind if I coyf?" She, of course, obliged.