What's black and green and seen all over? Blackwatch plaid. The signature tartan of the 3rd Battalion of the Royal Regiment of Scotland (known as The Black Watch) is popping up everywhere from waxed cotton outerwear and hopsack suiting to woolen accessories and button-down shirts. Ideal for any winter wardrobe, the pieces are especially suited for swanky holiday parties. Just remember to sport them one at a time.