look up any word, like sparkle pony:
 
1.
when someone takes a dump and the foul odor overtakes the rooms adjacent to the bathroom, at which time the person who took the dump tries to blame the stench on an unrelated source. happens when the social setting does not allow others affected to flat-out ask if the person just took a nasty dump, such as when it was an old person or your bosses wife. Name derived from a pervasive dropper of said bomb.
son: "what is that smell!!!???"
sons fiance: "yes it is very stinky, like how do you say....ummmm...sewer?"
mom: "Yes, I know, I called the front desk and told them to send maintenance because there must be something wrong. Someone will be right up."
moms husband: "I don't smell anything"
maintenance man: "there is nothing wrong with the sewer. someone dropped a st. pierre bomb in here. it'll clear up in a couple hours."
by gordon April 14, 2005
 
2.
This word is quite common in Boston, I have also heard it in South Eastern Ohio.

The definition I would say is slightly different than what is listed. Normally the person denying the source of the St. Pierre Bomb is someone other than the one who took the dump.

It is usually the bomber's good friend, spouse etc.
Nobody will ever fess up to that st. pierre bomb
by Bobby April 16, 2005