The sweat that forms on your balls when you're fucking your sister. May also be applied when fucking your hot female cousin, i.e. incest.
by Bushpig61 September 05, 2010

Man, it was hot out last night! My pants were soaked from the relative humidity when Ida and I came in from the porch.
by John Vanderlay March 22, 2008

Man, I was looking at those family pictures of Helen at Disneyland, I had some serious relative humidity going on in my pants!
by PSA Pilot February 18, 2010

by Anonymous September 18, 2003

by CASEY CARMAN January 23, 2009

It's that little drop of sweat that beads up on the back of your neck and dribbles down your back, thru your crack and eventually drips off of your ball while your fucking you sister.
by Pat May 14, 2003

by Nicole December 13, 2003
