I'd say it woukd be American as the word "mom" is used. For us Aussies it's not a breakfast drink whereas shakes are now being put on the menu as an alternative to breakfast. My favourite was chocolate until I was made a special avacardo milk shake by a Chinese girl serving at a local club bistro. It tasted wonderful.
I only have milkshakes after I've donated blood at the Blood Bank! I use to have lime, but they don't have that anymore, (I wonder why?!) so I now have chocolate. Next time I go, (in Dec) I'll ask for a caramel 1.