Personalized Best Grandpas Have Mustaches Youth T-Shirt. Youth T-Shirt - White with old time baseball style text that says THE BEST GRANDPAS HAVE MUSTACHE'S with a big handle bar mustache for the word MUSTACHE. Let the good times roll in a durable T-Shirt that takes kids from school to play in an amazing array of colors. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar.