There is a new product on the market (for "real" babies) that was invented by a mommy.
As you all know, if a baby is wearing a Onesie, and you suspect that they have messed their pants, the only way to check for poop is to either:
(A) Sniff the baby's bottom.
(B) lay them down and peek through the leg opening.
(C) Unsnap the Onesie, lift up the back part, and peek into the diaper from the back. (Kind of a hassel with a squirming infant.)
Well, now a real life mom has invented the "Peekinz Pocket". She makes sleepers and Onesies with this special pocket on the back, that lets a mom to simply peek in the back of the diaper and check for poop without having to sniff the baby's bottom, look through the leg, or take off the whole Onesie.
Here is the link, with a beautiful picture of a mother checking her baby's diaper for poop using the "Peekinz Pocket."