green eggs and ham
1.  A guy's first time he 'accidently' slips his cock into his girl's asshole while banging her doggie-style.  

2.  A guy's first time dry humping his boyfriend when his cock 'accidently' slips into his boyfriend's bunghole.

"Green" because he thinks he invented this ploy.  Ham for her ass.  A Dr. Seuss reference for all the parents in the world who can now read this story in a new light.
Susie Sweetbread was so wet, that while I was slapping my slender hips against her nubile hind end, when my tender young boner popped out of her twat and into her virgin stankhole, I didn't know we was making green eggs and ham till I looked down because she was a screaming for glory.