I have sometimes used the word colloquial to describe words on this blog. I should explain that colloquial does not mean slang.
Slang is a kind of language occurring chiefly in casual and playful speech, made up typically of short-lived coinages and figures of speech that are deliberately used in place of standard terms for added raciness, humour, irreverence, or other effect; language peculiar to a group; argot or jargon.
Colloquial is often assumed to mean slang but it doesn't. It simply means as used in a conversational sense; used in ordinary conversation; not formal or literary. Even a look at its synonyms yields ‘everyday’, ‘common’, and ‘idiomatic’ but not slang. Colloquialisms are therefore perfectly acceptable in conversation whereas slang may or may not be.