Sex juices, particularly semen, that head downhill due to gravity if a women stands after sex.
I tested my daughter's panties with a kit from www.infidelitytoday.com and found something that shouldn't be there.
by Nathan March 31, 2003
the biological term used by sexologists to describe semen leaking back out of the vagina after unprotected hetero sex is flowback
I rolled over into the wet spot, woke up, and cursed the flowback.
by Nick Mass January 27, 2005