when a male swings his junk between his legs fast enough to produce a "slap" sound. The maneuver is most effective in a North/South fashion. East/West will do, but it's not as loud and hurts your balls.
It's not a party until a someone does the slap for the ladies.
By Pansie
Slap On
A dildo that has some form of adhesive, that literally allows it to be slapped on, over the woman's vagina. The infamous danger being it detaching in a compromising position, such as pegging.