It’s not a proverb so much as an expression of disdain or indifference. In common usage, only the first two words are used—with a suitable expression of boredom or nonchalance, while pointedly not looking away from whatever you’re doing at that moment: שמחת זקנתי… (Simhat zqenti…)
Literally, it means, ‘My old woman’s happiness for all to see’, and is a translation of the Ladino (Judaeo-Spanish) expression, La gracia di tu mana (‘Your mother’s happiness’)—i.e., ‘[That might make my mother happy, but] I couldn’t care less’.