When I've told my friends I use to have sex with my sister they thought I was kidding. I told them it was true but no one believed me, first because of my reputation of being a liar and second because of my sister's reputation of being not-into-guys. As a last resource I've made a bet, I would record it on video and show them if they paid, and paid well. I think they accepted because they didn't believe me but here's the prove...