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noun - soap used exclusively for the purpose of cleaning one's hands pre-or-post finger bang (fb).
1) Dang, that girl Gina sure is stanky! I hope you used the fb soap after you guys hooked up at the party.

2) Melissa noticed that her lover's hands were dirty from working in the garage, so she broke out the fb soap in case they decided to get busy before dinner.
by Muscelly Mens September 13, 2011