Mom and dad are out for the evening and left me in charge because I'm the oldest. I check on you to find out that you were trying to jerk off! I notice you are having trouble so I over some encouragement, after all, I'm your big sister and I only want what's best for you baby bro. I finish with a count-down game just like when we were younger and encourage you to spy on me in the shower while I clean your cum off of me