English is a complex language with so many nuances that the rules of usage are forgotten in education systems. Is that because the teachers are not competent in the usage of the language they are teaching?
Puns are for children, not groan readers.
Go around the barn at high noon to avoid colloquialisms.
Even if a mixed metaphor sings, it should be derailed.
Who needs rhetorical questions?
Exaggeration is a billion times worse than understatement.