What is your underrated South Park episode?

Everyone knows the famous episodes, but in your opinion, what do you think is a completely underrated episode that doesn't get the love it deserves?

My nomination is W.T.F.

Just watching the boys turn wrestling into theater, Irene being addicted to abortions, breaking out into musical numbers during the tryouts, Vince McMahon and his theater binoculars.

It's gold.

What's your underrated episode and why?