e, by Matt Beaumont. It’s a novel in the form of several weeks’ worth of emails at a dysfunctional advertising agency. Roll-on-the-floor funny.
I second/third/eighty-seventh (whichever it’s gotten up to for each of them) Terry Pratchett, Christopher Moore, Gideon Defoe, and Jerome K. Jerome.
Since no one else has mentioned him, Spider Robinson’s Callahan books are wonderful. My favorites are the original (Callahan’s Crosstime Saloon) and the related (but not quite the same) Callahan’s Lady.
You have to like puns, though. That’s important. 
I had no idea this was a book. I just found out a few years ago, it was a movie before the TV show.
My suggestion IF one likes “Hitchhikers Guide” & Wagner’s “Ring”, Tom Holt’s “Expecting Someone Taller”- a modern-day sequel to the Ring Cycle.
Most of Tom Holt’s stuff is hilarious, but the man can’t write an ending to save his life.
Didn’t read post #95 in this thread, eh?
Sorry, it’s what I get for posting from work…sometimes I skim WAY too fast.
I read Thank You For Smoking this weekend and was laughing like a mental patient on the bus. It kept the seat next to me empty, so, for the best. After such a stellar recommendation, Pyrates was also bought. Thanks.
Ditto. The Pyrates is actually back in print, though unfortunately without the anonymous cover illustration of earlier editions. It’s also, for my money, the funniest of Fraser’s books – what constraints of historical plausibility exist in the Flashman books are ignored with abandon here, allowing freer play for Fraser’s wit and prose style.
I’ve also failed to find any mention of Tom Sharpe so far in this thread. Riotous Assembly and Indecent Exposure make the apartheid-era South African police funnier than they have any reasonable right to be. The Great Pursuit does the same for the publishing industry. The others are extremely funny as well, but these three are my favorites.
I’m not sure if it’s been mentioned in this thread before, but I’ve just finished Vernon God Little by DBC Pierre, and it was one of the funniest books I’ve read in a long time. Plus, it’s not too taxing if you are looking for something light at the moment.