As much as I wanted to like this episode, I really didn't. I blame the lame ending.
Good things first, though:
The idea of South Park - and the whole world - turning gay (or at least metrosexual) was amusing. I think that would have been enough to fill the episode, seeing the kids at school discriminate those who didn't want to go along with the new trend, and to see the daddies on a shopping spree in the mall.
Mr. Garrison's reaction was also amusing - and perhaps there is a little truth in it: seeing people take influence from the gay culture can lead to awkward misunderstandings.
Then along somes the crab people. Lame as hell, not funny at all, and it totally ruined the episode. Couldn't they come up with ANYTHING else?