The quests Delirium and Acute Delirium(which take place in the same inn) are full of these moments. Due to interaction with creatures from Xoriat, the realm of madness, you: teach a key a lesson, have a drinking contest with beholders, fight hambies(zombie ham), can grief an Elder Beholder that wants to solve a tile puzzle, fight puzzle tiles, escort beds and bookcases to form an airship, travel to Xoriat in the airship while holding off beholders from boarding said ship, and going into a giant beholder to receive the scepter that caused all of this.
You forgot the best part: to escape said giant beholder you have to make him puke you and your party back up.
Also, the dialogue from the mimic that ate the scepter, the Dungeon Master, and the beholders make this quest even more hilarious.
In the quest Siegebreaker, there's a rest shrine located in a disgusting pool where the enemy have been using it as an open air bathroom. If you're not careful and fall in, you get hit with a debuff called "What's That Smell?". And the ledges around it are VERY small.
In the same quest, detonating the Droaam bombs spawns two optional minibosses, a kobold and an ogre named Brinky and Pain respectively. Their dialogue ends with:
Yet another one from Siegebreaker; there is a (rather fat) half-orc miniboss named Skinny. He's the cook, and has an attack called Frying Pan in Face, complete with sound effects, a brief stun effect, and about twelve points of damage.
All of the Kobold dialogue in the Challenge Packs.
Otto's Sphere of Dancing . It's a disco ball floating in the air that....................makes nearly everything break into dance. It lasts up to 80 seconds.