The pact you WILLINGLY make in high school that when graduation rolls around and you are still a virgin, you have sex (full-on intercourse, none of this third-base or oral crap) with your best friend of the opposite gender regardless of circumstances, sexual orientation, feelings, etc.

Please do not rape your best friend. Mutual consent is required, seduction is allowed, protection is always necessary.
Steve: Oh man I can't believe you're going to college a virgin
Greg: Naw me and Kelsey made the Sex pact. I'm bangin her tonight
*highfives are exchanged*
by cherrypicker88 September 19, 2012
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When two high school senior girls make a pact that if they are still single at their 10-year high school reunion, they will have sex together. Typically the girls are very good friends or best friends and are not lesbians, and have never fooled around together previously in their friendship.
Girl 1: "Ok, lets make a 10-Year Sex Pact: if we're still single in 10 years, we'll have sex after our 10-year high school reunion."

Girl 2: "Alright."
by Tex-Mex Shawn C. September 21, 2010
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