The most common occurance of shomitting usually happens after or during a heavy night of drinking. The excess alcohol causes the victim to power spew. As the abdominal muscles contract in an effort to expell all your stomach contents out your mouth, unfortunately this abdominal contraction also encourages any poop chambered in your chute to also be expelled at the same time....
Can also occur if you get food poisoning and suffer from IBS.
Jenny: I need to spew
John: I'll hold your hair back
John: Holey shit, did you just shomit....that's disgusting.
The definition of the word Shomits is taking a shit and vomiting at the same time.
He woke up 7:30 am Sunday morning after drinking a lot Saturday night. He started to take a shit and in the middle had to vomit, immediately following he continued shitting. Now that is what I call a serious case of the Shomits.