One-Trick Pony

noun

a person or thing with only one special feature, talent, or area of expertise.

Some word experts say the idiom “one-trick pony” comes from the circus. A circus pony that can only do one trick is not going to entertain a crowd for very long. The term “one-trick pony” appeared around the turn of the twentieth century. Within about fifty years, the term had become an idiom.

Away with the Pixies

informal•British English

(see also: away with the fairies)

distracted, in a dreamworld, or out of touch with reality.

“you seem away with the pixies, are you listening?”

Pixies are: playfully impish or mischievous, prankish. 

pixie mood; a pixie sense of humor.

The origin of the phrase “away with the pixies” is unclear, but it relates to the folklore of pixies, which dates back to Celtic Britain and is particularly prominent in Southwest England. The idiom, used to describe someone mentally absent or flighty, suggests a connection to fairies taking or captivating people’s minds in folklore. While the phrase isn’t directly from a single source, it draws on the folk belief that pixies were mischievous entities capable of robbing people of their wits, as seen in stories and folklore. 

Enen a trained Monkey can do that

We need to be careful that we don’t offend the monkey community while explaining this one.

To all monkeys past and present, we honour you.

It would be phrased as such largely because the person doing it wouldn’t require much intelligence nor oversight – and likely the connotation that the person would also be paid peanuts. Not literally, of course.

All of this imagery is made to offend deliberately, and to derogate those who take these types of jobs.