Acronym for Bastard Assistant From Hell.
This being from hell of pure evil is usually found somewhere close to its executive counterpart the BOFH and supports him where ever it can. On occasions they may also be found alone in the dark backs of shops and postal services. BAFHs are always out looking for an opportunity to strike when you least expect it but without revealing its true identity or position.
I couldn't get a refund because of the bloody BAFH they got there