Fun Nite Chips are used for 1 or 2 nights prior to a casino opening in Atlantic City. The casino invites friends, etc. to play in the casino with these special chips so the Gaming Commission can review the casino's cash/chip handling procedures before giving them the green light to open. Think of it as play money (or Monopoly money, since it's Atlantic City). The casino charges an admission to get in, but the money raised is donated to charity. The play money currency in the catalog was used in the same way.

Most casinos have some sort of "dry run" before opening, but don't usually use specially made chips; occasionally they use generic chips instead. The recent pre-opening of Paris in Las Vegas included some nice play-money "Paris francs" in various denominations that was pretty.