So my girlfriend is from American origin but she has studied in Germany for a few years. I'm Dutch and she's been living with me for 5 (?) years now. She's getting to know the Dutch language well but sometimes words get mixed up.

The Dutch word for Ascension Day is Hemelvaartdag, shortened Hemelvaart. So, mix in some known German words that look like Dutch and you get Himmelfart.

Himmel fart: Stinks to high heaven!