Pump and Hump
When a woman's breast milk is used as a sexual lubricant.
"My wife is still breastfeeding, so I asked if she was down for a pump and hump."
Pump and Hump
When a human of the female gender, pulls her tits, or the male counterparty pulls them, untill she squirts breast milk onto the male dick. The male then inserts his penis into the females vagina using the milk as a lubrication.
Your having sex tonight? Well im going to Pump and Hump tonight Sister!
pump hump
To kill an enemy with a pump action shotgun or any shotgun in a video game.
I was lying on the ground sniping and this faggot ran up on me and pump humped me from behind.