We have experienced this twice. We heard it over the TV, dogs were on high alert, we were already in "Fate Accepted" mode because the Rhinoceros that was sneezing in the rack was already upon us and obviously very angry. When we realized we weren't dead, we looked at the rack to see one of the babies with its mouth open WIDE! Thrashing around like it was making the sound with its mouth.

Nastiest shart ever.