In British slang, "guff" is, among other things, a word for flatulation. This is true in both noun and verb forms, although more commonly in the verb.
Examples of usage:
- (sniffs the air inquisitively) "Hmm, Kenneth has guffed."
- (sniffs the air cautiously) "That was an impressive guff, Kenneth." // Not particularly common usage; may be deprecated.
Another sense is as a derogatory term denoting the low quality of any given thing. As far as I can tell, usage in this sense almost exactly parallels that of the word crap in the same context; noun and adjective.
Examples of usage:
- "The movie we went to see last night was pretty guff."
- "Scientology is a load of guff if you ask me."
There is a third sense of guff, meaning redundant, or overly verbose information. Usage in this sense parallels that in sense 2, noun form.
Example of usage
- I could give you examples from different areas of literature, television, film and E2 Writeups, in varying degrees of severity, with sidenotes on appropriate tone of voice, yadda yadda yadda... but that would just be guff.
One important point to notice regarding the different senses of "guff": In the first sense listed above, the noun form refers to guffs as distinct and separate items, whereas the second and third treat guff as being an arbitrarily divisible substance.
Disclaimer: this is all taken from my own experience, and some of it may well only apply where I live. If anyone has further information please /msg me or (even better) add your own writeup below.