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The person who is on standby when your original plan fails. Someone who you can count on, but really would rather not.

Gracie: Gee, I know I said we would do dinner, but something better came along!!
Loni: Oh, wow, I understand, I am just so disappointed!
Gracie: Ok, but if my better plans fail, Then I will call you as the backup fuck!
Loni: Great!! Love you!
by sgtpepperanderson October 15, 2008
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