So, for National Mustard Day (August 3), French's thought to make mustard-flavored ice cream. They're selling their horrible concoction for a limited time on both coasts:
To celebrate National Mustard Day on the West Coast, Coolhaus’s location in Culver City, CA will have the ice cream available on August 2-4 and August 9-11. On the East Coast, New Yorkers can look for the French’s Mustard Ice Cream truck on August 1 and 2, before making its way out to the Hamptons on August 3...
August 2 Madison Square Park Brooklyn Heights (DUMBO)
August 3 Main Street Hamptons East Hampton Main Beach on Ocean Ave.
Or, you can make your own. Because, why not? French's leads the way: