These are various types of training pants for learning to use the potty.  Some pull on and off like real underpants, some can pull on and be unsnapped, if needed, to take off.  Having the snaps is nice for the occasional accident, it makes clean-up much easier.

Fuzzi Bunz Trickle Free Trainers $17.95 $15.26	Imse Vimse Training Pants - Size Medium $13.50 $11.47	Imse Vimse Training Pants - Size Small $13.50 $11.47
Mommy's Touch Crib Sized Mattress Pads w/fleece $34.00 $30.00