Sex Bet With Stepsister

Your stepsister's boyfriend thinks that she is a true sex goddess. You don't believe that for a second so you want her to prove it to you. Great evil plan right? She does not buy that but then she comes up with a better plan. A Bet. A Sex bet that you cant last more than 3 minutes with her giving you a handjob. Win or lose it's a win when you get a handjob from your spinner stepsister! Now the only question is how long can you actually last before shooting your load all over her?