Well from the 60s I'd have to go with "It's A Mad, Mad, Mad, World(Color WS 160min.) and the "The Great Race"(Color WS 160min.). They both are the best examples of "Slapstick" comedy out there and both are EPIC movies well over two glorious hours each.
For a more modern selection of 90s I'd go with "Date Movie" and "Not Another Teen Movie". Both are just way over the top, raunchy as can be, and as far from any "Political Correctness" as any movie can be. I think they are both rated (R).