n. — Food
a rolled, sweet bun, usually containing nuts, raisins, currants and cinnamon with syrup topping or icing (see Image 1).
Type: 2. Preservation — Sticky bun is a preservation from American English, as some quotations indicate that the bun itself originated in Philadelphia (see, e.g. the 1972 quotation) and US quotations predate Canadian ones. The term is listed in DARE dating to 1900 (see DARE s.v. "sticky bun" [1]). According to internet domain searches in Chart 1, the term is now more prevalent in Canada than in the US, although it is most prevalent in New Zealand overall. Sticky bun may be less popular in Canada than the equivalent term "cinnamon bun".
See also ITP Nelson, s.v. "sticky bun", which is marked "Canadian", and OED-3, s.v. "sticky bun", which is marked "N. Amer.". COD-2 lists the term, but does not lable it.
Images:

Image 1: A loaf of sticky buns. Source: Wikimedia Commons. Photo: D. Ramsey 
Chart 1: Internet Domain Search, 16 Oct. 2012