Yeah, that seems like something a guy would do worry free and proudly, especially a guy that "tapped his sisters pussy while growing up". If anyone wonders where this response is coming from, check out yoursmalldick's "other posts", the topic is "family member"
It's also great to hang out with your buds and scratch your balls together. When you've reached the point that you all feel comfortable scratching yourselves without feeling self conscious about it, then you know you have true friendship.
A - Because they don't have any balls to scratch.