Personalized Whatif Monster Birthday Girl Infant Romper. There's no day like your birthday, so why not try something new? Whatif Monster Birthday Girl Infant Romper - Natural, perfect for little fans of "Jonathan James and the Whatif Monster" by Michelle Nelson-Schmidt. Meet your new favorite outfit! Keep dressing simple with this one piece, lap shoulder t-romper. Super soft and perfect for baby's sensitive skin. 5.5 oz. 100% combed ringspun cotton premium jersey (CVC Colors are 60/40; Heather is 90/10 combed ringspun cotton/polyester)