Gravity Falls, Season 2

Agent Powers:
My name is Agent Powers, and this is Agent Trigger. We're here to investigate reports of mysterious activity in this town.

Agent Trigger:
(pointing at Stan) Activity!

Stan:
"Mysterious activity?" At the Mystery Shack? You must be joking!

Agent Powers:
I assure you, I am not. I was born with a rare disorder that prevents me from experiencing humor.

Stan:
(laughs nervously)

Agent Powers:
I don't understand that sound you're making with your mouth.