boob hump 

when two girls hump their boobs against one another

Bria and Stef boob humped one another.

boob hump by Coollio7 June 5, 2009

Boob-Hump

to thrust your chest, typically at another person, in a humping motion.

Danny wasn't pleased that Zach had tried to boob-hump him in front of his girlfriend.

Boob-Hump by Kendeisel October 4, 2010