When you intentionally unleash a nasty fart in in a small room like someone's bedroom or office.
I went to talk to my apartment manager and she was really rude to me, so I dropped a dirty bomb on my way out.
"Dude, someone just deployed a dirty bomb in here."
To properly lay a 'dirty bomb' one must first deficate on their partner's chest (in between the boobs) and finally must slap the boobs together (inward) to launch the fecal matter all over the face and lower areas.
While performing anal sex, the act of withdrawing prior to ejaculation and slapping the other on the forhead while cumming with the shit covered penis.
"Dude, I totally dirty bombed that skunt last night."