Canadian pronunciation of the word coupon

Traditionally, the retention of the diphthong [ɪu] (as in cute [kɪut]) is said to distinguish Canadian English speakers from American English speakers. Thus we assume the Canadian pronunciation of coupon should retain the glide and be pronounced [kɪupɑn]. However, as the word coupon never contained the [ɪu] sound, its "retention" in this word is actually a hypercorrection, and the true Canadian pronunciation of coupon is the same as the phonology in noon [kupɑn].

(ENGL 320: History of the English Language)