When Elders Price and Cunningham are waiting for their plane, an African sunset backdrop suddenly falls while a woman dressed in a Lion-King style costume leaps out and sings an Expy of the opening vocals to The Circle of Life. The curtain then drops to reveal it was just a surprise to send the boys off to Africa
The SMHD costumes alone are hysterical, from Halloween-style devil outfits with plastic pitchforks to maple doughnut hats to demons wearing giant coffee cups (who torture Kevin by force-feeding him coffee) to sparkly black top hats and waistcoats.
Elder McKinley, again, after waking Elder Price from the Spooky Mormon Hell Dream:
Elder McKinley: You had the Mormon Hell Dream? Was I in it?!
"I Believe" is a funny enough song as is. The fact that Elder Price is practically prancing up to a maniacal warlord and grabbing his hand, however, makes it priceless - the only reason that the General's men aren't shooting him is because they're too confused by what's going on.
General: ...The fuck is this?
"I believe... that in 1978 God changed his mind about black people!" (followed by the choir echoing "black people!").
Elder Price, after having the Book of Mormon shoved up his ass, gets completely wasted...on coffee.
Elder Price: Well, if it isn't Elder Cunningham! The super-mormon!
This is followed up by his monologue on why he became such a devout Mormon. He hoped that when he died, he'd get his own PLANET ORLANDO!
From "Baptize Me": I'M WET WITH SALVAAATIOOON!!!
It's hard to describe "Joseph Smith American Moses", but... "Joseph Smith, magical AIDS frog! Brigham Young, frog on his clit face!"
"Compassion! Courtesy! Let's be really fucking polite to everyone!"
The costumes and choreography.
Also, the summation at the end of the song: "Joseph Smith, AIDS frog; Brigham Young, clit face; Shit come out the butt; Jesus says 'fuck, fuck,' Mormons!"
The ending with the Ugandan Elders. "Hello, my name is Elder Matumbo..."
"Hello, my name is Elder Butt Fucking Naked."
"And if you put that gun down I will—oh, okay, I'll leave!"