Bulleit (Rye or Bourbon, depending), Campari, Aperol (or Peychaud's Apperitivo), and fresh lemon. It always amazes me how much this concoction tastes like *grapefruit*, of all things. Everyone I've made it for, so far, loves it. It's easy to make, and your friends will think you're a superstar. Just don't tell them the ingredients, unless they are adventurous.