he looked upon his toilet bowl, and realised he had laid an f-bomb.
Words like 'shit' and 'ass' no longer have much shock value. Fuck is the mother of all cuss words. But to avoid saying 'fuck' when refering to 'fuck', people call the word an 'f bomb'.
Person 2: O...k
Person 1: She got me a fuckin honey bun instead.
Person 2: and...
Person 1: Are you mocking me? Well, fuck you you fucking fuck!
Person 2: ...a tad happy with the f bomb, aren't we?
Use the f bomb sparingly, or it looses it's effectiveness.