Personalized Hippo 1st Birthday Toddler T-Shirt. Hippo 1st Birthday! I mean Happy 1st Birthday! A cute, smiling hippo wearing a birthday hat sits in front of a birthday cake ready to blow out the candle. Cute first birthday gift for the one year old! A toddler-soft cotton tee in look-at-me, big kid colors. 4.5 oz., 100% combed ringspun cotton. White is sewn with 100% cotton thread. Topstitched rib crew neck. Double-needle stitched sleeves and bottom hem. Shoulder-to-shoulder taping.