I feel like an idiot, but what is the butt flap for?
Doodle Pants | Daily deals for moms, babies and kids
I think they just build extra fabric into the bum to make it roomy enough for diapers (my DD's diaper would always manage to push her tighter leggings down). Here's another shot: Doodle Pants in Rocketship for boys
THANK GOODNESS I'm having a boy or I'd buy about 6 of those...the girl ones are adorable!! Not so into the leggings for boys thing but that's just me.
The butt flap is for added cuteness!