If you don't own diapers you can make some using trash bags, paper towels, and tape like this:
http://www.youtube.com/watch?v=QnkCiKm_gP8
Or you can take a towel, stuff it into those same wet panties you were using before, and cover the entire thing with a trash back (cut holes for the legs)
Either way, pretend mommy has lifted up those legs, played with you to tease you just enough (yes sissies, you can play with yourself in this position a little bit) and has put you in your comfy diaper!
Maybe mommy was really naughty and rubbed a finger up against that pretty ass of yours, maybe slipping it into your boy-pussy?
Hmmm that'd be fun ;)