why toilet humour

But the point of that scene wasn't .... ok, if you've never been in that 'situation' or close/similar, you may not get the humor...it wasn't a 'fart joke' necessarily - it was about the dating ritual and things that seem to happen at the most inopportune times while trying to impress your 'date'.
I can't stand toilet humor and I'd be uncomfortable watching this flick with a date.Having said that, while sitting here alone watching it on tv, I have to say I was both squirming in my seat and laughing my a** off.
Maybe you've been in the 'situation', maybe its a common 'situation', I wouldn't know as its not a 'situation' I'd be comfortable talking to others about. And maybe this is your point - maybe its happens to everyone at some time but you find it unnecessary and crude to immortalize (the 'situation')
on film ?
I can respect that opinion. It must be hard though to come up with 'fresh'/original material as all the top comedians have covered just about everything imaginable. If it was toilet humor just for the sake of making a childish joke I'd agree - there are plenty of those low brow flicks out there.
With comedy its a crap shoot (no pun intended). If the majority of your audience can't 'relate' to the joke, the joke falls flat. Judging by the '2 stars' rating this movie was given in my local movie/tv listings I'm guessing most people feel as you do. I'd guess that we were the intended 'target audience' though because it wouldn't be funny to those who are less troubled over bodily functions. I know guys who would have just yelled out 'Hey Polly, what the deal with the toilet paper here ?" and thought nothing of it. I'd have reacted more like the Stiller character. Guess whos life is less complicated ?
I saw 'Theres Something About Mary' having NO idea what to expect - it was one of those last second decisions to 'go see a movie'. I was floored through out and very thankful I was only in the company of male friends. Now there was a movie with one contrived situation after another - contrived solely for shock value and not 'observational' humor unless you hang with a very strange crowd.
*My younger bro did get it caught in the zipper once so I thought we were off to a good start :-) I never assumed this ever happened to another male but in my world, it did. Most of what followed though was pretty damn shocking and contrived for the sake of being 'shocking'. IMHO, there is a difference.
This is sooo easy to 'talk about' on the internet(s) - if we were in the same room though I wouldn't even think about discussing this !