Bottom Grinding 

Homosexual Dry Humping.

19 yr old Dave was nervous about going all the way with his 46 yr old lover Joe and wanted to take it slow, so they just did a little bottom grinding.

Bottom Grinding by John Thomas269 January 29, 2009

Bottom Grinding 

dry humping with only your bottoms on

"She wanted to take things slow, so we just did some Bottom Grinding for a few hours" or "She was on the rag, so Bottom Grinding was the only clean option"

Bottom Grinding by Brock Lander February 5, 2009