Verb. and Noun. This is the act of "accidentally" going from vaginal to anal, and then directly back into vaginal intercourse, using the "Oops wrong hole!" excuse.
This is meant to purposefully cause a yeast infection of the WORST caliber. (Solely reserved for those women who are cheating on you or on someone else with you.)
Lou:"Brad, i don't know how to tell you... but i think Melanie's cheating..."
Courtney:"Brownie Bomb that bitch."
To defecate in the exhaust pipe of one's vehicle
John's brownie bomb backfired onto the neighbor's house, dog, and front yard.