The face a man makes when he orgasms. It is said that when you look into a man's eyes while he has his Vinegar Strokes, you can see into his soul. Its also the point in sex where you can't stop and have to finish.
Cathy: "So, how was Jeremy last night?"
Jasmine: "Amazing! He has a funny Vinegar Strokes though."
Jake: "Dude, I called. Why didn't you pick up the phone?"
Jeremy: "I wish I could've, but I was in the middle of a Vinegar Strokes."
Jake: "Oh, I understand."