When two people in a sexual relationship insert their fingers/fist into each other's assholes while in a 69 position.

When two uncircumcised men are snoodling and the one with the girthier penis pulls back his foreskin, exposing the head, then the skinnier penis wraps his foreskin around the head of the larger, followed by the larger wrapping it's foreskin over the skinnier penis's foreskin.
For added suction, add water under the foreskin and let evaporate.

Can also be referred to as the "Super Snoodle"

The act of two men pulling back their foreskins while touching tips. Once both heads come together both partners shall release the hold of their foreskins, therefor both foreskins shall come together forming an unbreakable seal.

The act of two man fornicating with a double ended dildo, the pressure stimulating both of their genitals but also keeping them trapped in the device.

When you're fingering a girl, and she sneezes. This causes the tensing of the vagina muscles which can get your finger stuck up there! :D

A form of handjob where the woman places her palm on the head of the penis, draping her fingers down over the shaft. The woman typically then lifts her hand while simultaneously bringing her fingers together. This is generally used in "fooling around" situations, or by inexperienced women who don't really get what feels good and what doesn't.

When you and your buddy each put your dicks in opposite ends of a beer sock.