Oooh so many fans of Sir Pterry here!
Cloverjo, he's not for everyone, but I'd recommend Mort or Guards! Guards! If you're ever inclined towards some Rincewind-free Discworld. Alternatively, if you want some giggles from another source, Robert Rankin is wonderfully ridiculous, Jasper Fforde's Thursday Next books are great and dear old Douglas Adams also gets dusted down if I'm feeling blue and need cheering up.