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 by Fappus the Bold April 10, 2009

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 and Hump by Fuckboy69#chris in the cafe January 18, 2017