I was alone with my sister-in-law, who is missing her chance to get married, at my wife's parents' house... I haven't had sex with my wife recently, so I was attracted to her feminine charm and entered a fantasy mode of her seducing me! When I got my dick hard and started stroking it, my sister actually found me. I thought this was a bad idea, but then... I was met with a godly response from her pussy.