Doctor uses techniques to increase length of teen's penis

A guy goes to his doctor because he's insecure about the size of his dick. The doc assures him that it's all about technique and proceeds to give him a handjob to prove it. He makes the guy stroke his own cock while he licks his balls, then he works his magic on the girl's pussy, making her moan in pleasure. The doc then has the girl suck his cock and the guy strokes his own while watching. They all get off together and the guy is much more confident in his skills.