I created a race once, aside from my penguin people, (Which I shan't let you use, no offence. Your storywriting is simply too serious to contain them, though the ones I am suggesting are anomalous gags and are better left as npcs.) they are a race of men in color-changing gimp suits who jump out of random places and scare the living shit out of people. They are called "Blehs" because that's what they say. Here are some examples of how a Bleh would be used in a story. I'd go into the questionable history of the Blehs... But it's better left unexplained, they're funnier that way... reading this over, I'm sure you'll stick to the mind-flayers...
Direct Encounter Ex:
Adventurer: What a fine day to go adventuring!
Bleh: *Jumping out of a random corner* BLEH!
Adventurer: HOLY SHIT!
At that point anti-climactic combat would ensue, ending with the Bleh being murdered horribly.
Indirect Encounter Ex:
Office worker (I'm sure you'll have a suitable city): Ah finally, a long day of getting my work done is over.
A DESK DRAWER SPONTANEOUSLY OPENS AND A WILD BLEH JUMPS OUT!
Bleh: BLEHH!
Office Worker: (something along the lines of "HOLY SHIT!")
At this point humorous dialogue would ensue, in which the Office worker is repeatedly harrassed by the Bleh's comeuppance throughout the rest of the week, resulting in a quest for the adventurer to find and remove the Bleh from the office worker's life.
And the worst possible use of a Bleh....
Two protagonists getting down and dirty (in the sexually arousing way, not the combattive way)
AND SUDDENLY A BLEH JUMPS OUT OF [... Sorry kids...]
Bleh: BLEHH!
Protagonists: OMGWTFBBQ!?!?!
You get to decide where to go with that one if you're effed up enough to use that...