Trench Mortar

The act of pulling out, placing your penis between the other persons butt cheeks aiming upwards, and yelling "fire in the hole!" while finishing on there back.

I didn't know if she was on birth control so I pulled a trench mortar.

Water lizard

When a man submerges himself to his neck in a bath tub and begins masturbating underwater.

I got so bored last night, I did a water lizard.