Personalized Monster Truck 3rd Birthday Youth T-Shirt. I'm Three! A red monster truck drives over the words. Great third birthday gift for your 3 year old who loves trucks. 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.