The happy hour deal runs from 2 to 5 PM on weekdays at participating locations. Besides small smoothies for $2, small iced coffees are $1 and small Ultimate Frappes are $2 during happy hour.
It looks like they tried to cover a little bit of everything for the deal whether you're looking to indulge, looking for something a little healthier, or looking for a late afternoon pick-me-up. Interestingly, there's no soda or fountain drink including in the promotion (which probably would have been cheapest cost-wise).
Image via Dairy Queen.