You should study human anatomy more - muscles expand and contract. Big things up me for years (and mine up others) have never caused any problems. Stop being a nellie - or go watch the Disney Channel!
This young man will have problems when he is older. The Sphincter ani externus (external anal sphincter) is a muscle that stops shit coming out of your ass. If this lad continues stretching it like this he will be shitting in his pants by the time he is 50 years old.
