Personalized Cowboy Groom's Posse T-Shirt. Cowboy groom's posse! A country western themed wedding has groomsmen who are cowboys, and together they make a posse for the newlywed groom! For when a cowboy and cowgirl get hitched. Wardrobe essential for looking good, 24/7. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar. Shoulder-to-shoulder taping. Double-needle stitched sleeves, bottom hem and front neck. Note: greys are a cotton/polyester blend.