A mischeivious individual, harmless in nature, but always to be'n a brat. Noun. A miscreant, a corrupt person, an untrustworthy individual. Cf. 'good egg'. Bad Egg produces a pungent smell, and is inedible.In urban terms, Bad Egg, is comparable to Bullshit except that Bad Egg undoubtedly causes violence or stress, whereas bullshit is over looked.