I’ve got a black joker card in my wallet. I was walking to the tram stop with someone once, when I saw this playing card face-down on the floor, so I said “bet you I can guess this card,” I knelt down, and I said “I think it’s a joker.” I was about to turn it over when my friend said “hold on, black or red?” I said black and turned it over, and now it lives in my wallet.
One thing I can tell you with confidence about the Netherlands is that people there almost invariably overestimate their proficiency in English, so adverts and public announcements and the like in English often have embarrassing mistakes, so I’d put money down that they’re not going to hire a native speaker or perhaps even a chartered translator to check the translations.