Brother teaches sister how to give blow jobs

A naive, innocent schoolgirl walks in after being at school, wondering if her big brother can help with something. Everybody at school, both boys and girls, have been talking about blowjobs. She's embarrassed because she's never given one before, so she asks her brother to teach her how to give one. "What the hell!? You're my sister. Oh well--put this rain poncho on, so your school clothes don't get dirty. Put this condom on my cock." She gets on her knees with her poncho