From The Collaborative International Dictionary of English v.0.48:
guff \guff\ n.
1. A ludicrously false statment. [WordNet sense 1]
Syn: bullshit, bull, Irish bull, horseshit, shit, crap, bunk,
bunkum, buncombe, rot, hogwash, dogshit.
[WordNet 1.5]
2. Insolent or disrespectful talk; as, don't give me any of
your guff, young lady.
[PJC]