2. When a girl is fellating a man, upon ejaculation, the penis is removed from the mouth and the semen covers her face. At this point she will probably close her eyes to avoid the sting, which is the sign to punch her square on the nose and take a photograph. For perfect JD'ing, wait a few seconds for the redness to appear.
The red blood represents the jam, and the semen is the doughnut and icing.
"Yeah, but he IS eating an entire bucket of jam doughnuts, he's my idol."
"He's basically a jam doughnut."
2. "Dude, I JD'd my girl the other night."
"Really?! That's awesome! What did she do?"
"Called the cops."