What's an "average" guy?

Lately I've been wondering, what makes an average guy average? I realize I probably should be able to answer this question, since my parents did my best to raise me as a boy, and as an adult I didn't get called ma'm when I was trying to pass as a guy. Just the same, guys feel like a mystery to me.

The reason I ask this is because I've tried to portray Carl (the big brother in Shoes and Brianna's Big Brother) as an average guy, but I'm wondering how off the mark I've gotten. For instance, in the second chapter of Brianna's Big Brother, he's putting flowers in his sister's hair. While it's something I wouldn't think twice about doing, is it something the average guy would do? Is there a way of making sure my male characters feel realistic?