In Finnish we have “kissanristiäiset” (literally means a cat’s christening), which means some trivial and meaningless celebration/event.
When you want it both ways but cant: “You want to blow with flour in your mouth”
Oh I like this one
In French we would say « You can’t have the butter and the butter’s money »
One usual extension of the expression is « You can’t have the butter, the butter’s money and the creamer’s butt »
When there’s no reason to hurry « y a pas le feu au lac » (« the lake isn’t on fire »)