I’m your younger stepsister and you’re helping me with math lessons. I’m very bored and I don’t understand anything in math. So I propose you to go for a walk or to play. While begging you to stop the lesson I accidentally fart. I’m very embarrassed, because I secretly have a crush on you. But I notice that you’re not mad and your dick became hard. I tell you that I have a crush on you and obviously you have a crush on my farts. I’m going to help you with the hard dick to suck it while farting. I fart more while sucking your big hard dick and let you cum in mouth. Thanks for the good lesson, stepbro