Someone that is a punk, but smaller than a punk. Hence a little punk. See also greek definition Littious Punkious.
It's like when Jennifer Brantley is supposed to let you know she is going to the airport so you can be a gentleman and giver her a ride but then all the sudden she textes you saying "I'm already here. I was kind of hanging out. I'm leaving in a few"... Then all you can say to that is - "What a little punk!".