A penis that is small when compared to other guys. It resembles a little boy's penis especially if it has tiny balls to match.
A lot of girls like a small penis because it is fun for them to play with and will still pleasure them without hurting them.
I have a small penis and my girlfriend loves to play with it. She calls it her toy and loves when it is inside her.
Guy in locker room: "Dude, I never saw your dick before! My six year old brother has more meat than that!"
Me: "Dude, my girlfriend loves sucking it since it is small and cute. She also thinks my balls are fun to play with. I am so lucky to have a small dick that girls love!"