Really? My sister rented it last week - she said it was hilarious - I thought it was possibly the dumbest movie I'd ever seen. Maybe I just didn't get it. It felt like the lead up to a joke without the punchline ever being revealed.
Different folks, different tastes, I guess.
The point is that it IS dumb.
It reminded me of something my brothers would come up with - completely random stuff. And no, there's no plot.
But I still thought it was funny. Not as funny as my siblings did, but funny. It gets quoted a lot.