To not show up. When someone tells her friends she'll meet somewhere at a specific time but then is a no-show either because she forgot or even more likely because she never intended to show up to start with. Example: Halley's obviously giersched on us again. Halley's a giersch. (Noun)
GIERSCH
Meaning of GIERSCH in English
Slang English vocab. Английский сленговый словарь. 2012