It was an excellent discussion in Y12 Lang yesterday (well, I enjoyed it, anyway). The word I was looking for but couldn’t recall was mondegreen.
Interesting related phenomena include eggcorns . Fran asked about those words such as ‘gormless’ that look as though they are derived from a word (here ‘gorm’) that doesn’t exist. There are plenty of them, and they are known as unpaired words or absent antonyms. We also considered the concept of back-formation.
The concept of liffs is very similar to sniglets, while the meaning of ‘liff’ itself in the definition given in the link in the previous post has been altered from the original definition in The Meaning of Liff. Liffs seem always to involve the use of a placename to provide the lexeme, while sniglets can be created using a range of normal processes of neologism.
Although a lot of this material seems fairly trivial, or just for fun (and what’s wrong with that?) these examples of linguistic curios and wordplay can help to improve your knowledge of lexis and morphology.