I call you into my room and ask if you can check out my flex poses for my gym's upcoming show. I strip down to my bikini and start flexing, then notice you have a boner. I'm shocked but sort of proud of myself for being able to do that to my own step-brother. I get so turned on by it I try and convince you to jerk off to me, I mean I won't tell anyone and I think it would be pretty hot. You're way too hesitant and embarrassed so I tell you I'll go topless if you take out your dick. I really want to watch you stroke it so I make a deal, if I masturbate and cum so will you. After I finish up you're really close to cumming, I get up and show off my abs and flex, then encourage you to cum!