I'd recommend Tropic Thunder over Pineapple Express, though if you've basically got the whole day open, I'd do a double feature.
Issues with the Tropic Thunder crew? Guess I don't read the boards as much as I once did...
At any rate, I don't think I've laughed that hard out loud at the movies without being totally high (and I'm sure I was annoying as **** that night... but let's not go there). Only trouble with the awesome lines is that the guys who kind of talked in that 'commentary kind of way' (you know, when people say awwwweeesommmmme at a good scene...) would repeat the best quips.
Normally, there comes a point where I've gotta shut them up or I start to get really pissed, but I was having so much fun I decided against it. For those who might find it amusing...