For a while now, some folks familiar with “secret menu” items at McDonald’s looked forward to Shamrock Shake season because it meant they could talk McD’s staffers into making a combo mint/chocolate version of the frozen treat. Now the fast food chain is putting this do-it-yourself option on the actual menu, at least for the next few weeks. The new McCafé Shamrock Shake line is already rolling out to some restaurants. Not all McDonald’s franchises are participating, so keep that in mind before you head out early in search of them.