Wow, just five is difficult and I do wholeheartedly like the majority of films already mentioned.
If it really must be five then I think, for now, it has to be:
Pulp Fiction
Monty Python's The Life of Brian
Das Boot
Full Metal Jacket
Apocolypse Now
But I must also give an honourable mention to
Jason and the Argonauts (1963 version) which should also be in that list as I believe that it truly is a great film, and the animation I find better than
most of today's CGI trash. And a funny fact about the making of the film during one shoot a replica of the Golden Hind came into view - and the producer shouted "Get that ship out of here, you're in the wrong century!"
It would, on some days, knock off either Apocolypse Now or FMJ.