drop a bomb

verb2

1. •
   (UK, slang) To release noxious gas from the bowels: to fart.

   • Let's say you're at school and you accidentally drop a bomb in class. Try coughing or dropping a book to cover up the sound. — 2004
2. •
   (US, slang) To release feces into a toilet; to defecate.

   • To drop a bomb in the public toilet. — 1989