42" Mardi Gras Jester Hat Balloon. Accent your Mardi Gras or Fat Tuesday themed party with this 42 inch large unique shape Mardi Gras Jester Hat foil mylar balloon. The perfect balloon for your Mardi Gras or Fat Tuesday party, this 42 inch Betallic party balloon is great for setting the scene! This balloon includes a self-sealing valve, preventing the gas from escaping after it's inflated. The balloon can be inflated with helium to float or with air.