Din is a rather... unusual Redguard encountered north of Gnisis. He apparently lost his mind when he was bitten by a slaughterfish, and his fever is making him say very interesting things, like: "Muddled? Where? No! Don't play in the muddled. You'll get a dirty mind."
When wandering the countryside, you might run into a naked Nordic barbarian standing around. He claims a witch stole his clothes. Elsewhere, you might encounter another Nordic barbarian claiming a witch stole his clothes. And a third. There's also one in Tribunal, but he insists that he was only naked because of the heat, and complains that everybody thinks a witch stole his clothes.
And just in case you didn't get the joke, there are a couple of bedrooms where you can find potions of Fortify Endurance under or behind the bed.
Dagoth Ur's reaction when you start attacking the Heart of Lorkhan.
The "Favors for Orcs" quest. It involves two orcs trying to hide from the guards for whatever reason, and you must play messenger boy between them. The first gives you a note to give to the other orc, saying that he's hiding "by the tree near a rock and another rock". He says that he's "good at hiding, so if you don't see me, that's where I am". When the quest is over, your journal notes that you "feel a bit stupider for ever having talked to either one of them".
Speaking of orcs, Ghorak Manor in Caldera has a few humorous areas. Creeper, the friendly Scamp with the 2nd most gold to barter in the vanilla game is on the 2nd level. Elsewhere, there is a female orc in a bedroom wearing armor up top... and nothing down below.