Feeling lucky? Minneapolis-based Caribou Coffee is celebrating St. Patrick’s Day by offering a buy-one-get-one FREE beverage today, Friday, March 17, no luck necessary. The offer is valid on any beverage, all day. (Typically, bottled beverages are excluded from such offers, so you may want to ask first.) To get the bargain beverages, you MUST mention the BOGO promo at checkout. (The promo was announced via its Twitter account.) There are 22 locations in Colorado, with 18 in the Denver metro area.