be a bomb—(coll.) be a failure or fiasco:
- Unfortunately, the film was a bomb and gained a reputation as being the only film on which Mr. Corman lost money.
be the bomb—(U.S. sl., sometimes spelled “be da bomb”) be very successful; be received enthusiastically:
- The show was the “bomb” back in the day when it first aired.
Note: The expression does not correlate in meaning with the phrase make a bomb—(sl.) make or earn a great deal of money:
- Many of them are too honest to do any [drug] trafficking but the ones that do make a bomb.