Malapropism

A malapropism is the inappropriate use of an otherwise perfectly good word. "Casting nasturtiums" is one that has fallen in to such popular usage that I couldn't find any obvious beginning to it.

I used to go out with a chap who was a malapropimaniac. This was years ago so I am free to laugh about them in public. For example:

Onion Bungee = Onion Bhaji
Lynch = Loach (a fish I had at the time)

The absolute topper was one time when three of us were planning a cycling trip and what to take. He seemed very keen to bring my fondue set. Not only do I not (and have never) owned a fondue set but I couldn't think why he'd want to lug one round on a camping trip or how we'd use it. The other friend and I knitted our brows at each other but couldn't work this out. We eventually realised he wanted my triangia stove...