This is the classic Canadian term used in everyday conversation. The word can be used to end a question, say “hello” to someone at a distance, to show surprise

A loonie is a Canadian $1 coin with an image of the Canadian bird, the loon, on one side of the coin.

The Canadian $2 coin was introduced in 1996, and the words “two” and “Loonie” became a single term, Toonie.