A Confederacy of Dunces by John Kennedy Toole (1980) and Porterhouse Blue by Tom Sharpe (1974).
A Confederacy of Dunces. This really is an incredible book, even funnier than I remembered it, and a bit sadder too. Ignatius is such an amazing invention โฆ grotesque in every way and a total tool, but somehow heroic. It could be dated given the setting (1960s New Orleans) but holds up remarkably well.
Porterhouse Blue is a bit more dated – but in recompense has some fantastically funny lines, and will be all-too-familiar to anyone who’s spent any time in a Cambridge/Oxford college.