Kodak - It's petrifying gaze only works when printed on paper, so it must quickly take a polaroid of itself and show it to the adventurers.
Retch (Demon) - It looks so disgusting that you roll a Fortitude Save or start to...
Barbara Wawa (Devil) - It bores people to death by interviewing them. "When the goblin hit you, how did that make you feel, I mean emotionally?"
Dire Balloon Animals - I'll let you all just imagine this one. Made by Shambling Clown, below.
Eye Gook Elemental - It comes from a plane filled with the stuff that you scrape out of the side of your eye...ewwww!
Grassy Gnoll - Has grass instead of fur, sometimes has a sniper on it's back also.
Night Nag - Keeps waking you up by snoring, or getting up every 10 minutes to go to the bathroom.
Gray Booze - Tastes great, but what a hangover the next morning.
Shambling Clown - Brainless plant thing with a red nose that juggles and spawns dire balloon animals.
Umber Hulk Hogan - (paraphrasing the MM) Umber Hulk Hogans are massive men that dwell deep within the wrestling world. Ripping through t-shirts as if they were...uhh, t-shirts, they rampage through movies and tv shows sporadically, leaving a wake of people reaching for their remotes.
Why, Vern? - Something that Ernest may have said.
Half-Friend Template (expanding on Mouseferatu's idea) - You apply this template to anyone who acts nice, then talks behind your back...or borrows money and never repays you...etc...