While receiving a blow job, discretely stuff confetti and/or glitter into your butthole. When you are ready to ejaculate pull out and aim for your partner's eyes. While your partner is temporarily blinded, turn around, spread your butt cheeks, and fart directly in their face. This should expel the colorful contents of your butthole with enough force that it will explode all over your partner's face, much like a Party Popper. If performed correctly the glitter and/or confetti should adhere to the ejaculate you previously plastered on your partner's face. Sit back and enjoy the masterpiece you've created.
I gave my girl The Party Popper last night. Her face looked like a birthday cake.