Personalized Monkey Future Big Sister Youth T-Shirt. Future big sister Youth T-Shirt - Kelly Green with adorable little girl monkey ballerina in a pink tutu and ballet slippers holding a bouquet of flowers says I'M GOING TO BE A BIG SISTER. 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.