Personalized Owl 100 Days School Youth T-Shirt. Funny 100th Day of School Youth T-Shirt - Kelly Green for teachers and students with 3 cute owls on a yellow ruler says 100th DAY OF SCHOOL. Celebrate being 100 days smarter. 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.