Thunderday
A different way than calling Donnerstag Thursday. It’s the Donnerstag when there’s a thunderstorm with heavy rain. In a German lesson you read the date saying Donnerstag 31. März 2022 and ask your teacher if it will thunder today when the writing meant Thursday, March 31st, 2022 which turns into Thunderday according to the weather forecast.
“Hey Mr. Zürcher, is it going to rain with thunder today? It’s Thunderday, March 31st, 2022!”