Drop A Bomb Meaning

(US, slang, euphemistic) To release faeces from the bowels; to excrete

Example: Used other than as an idiom: see drop,‎ bomb.
2004, Mahdi Obeidi, Kurt Pitzer, Bomb in My Garden: The Secrets of Saddam's Nuclear Mastermind, page 93,
  Three hours after Hussein Kamel left, he called my office and dropped a bomb on me.
  â€œPresident Saddam has asked to see you in person,” he said.
2004, Bart King, Chris Sabatino, The Big Book of Boy Stuff, page 129,
  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.
1989, Brian King, The Conceptual Structure of Emotional Experience in Chinese, Lulu.com, page 66,
  To drop a bomb in the public toilet.
2004, Michael Ryan, The Dirtiest Toilet Humor Book Ever, iUniverse, page 7,
  I had to drop a bomb! What the hell was I going to do? So I pulled down my bathing suit, lying on my back, with my ass in the water, and shat.
1998, ʻĀrīyā Chumsāi, ʻĀrīyā Sirisōphā, Mūat Po̜p =: Boot Camp - English title: Basic training (Military education), Fiučhœ̄ Phaplitching, page 79,
  ...prepare your backpack and MAYBE spare a minute to drop a bomb in the toilet?