a shot across the bow
Getting a blowjob and then the person pulls away just as you're about to finish, making you spray jizz on their face like a drunk kid at a soda fountain.
She was giving me a blow job and pulled away right when I was about to cum.
He stopped sucking my cock just as I was about to blow my load on his face.
She bit me and I cummed all over her chin like a baby.