Title explains it all, so I'll just post a few from Finland (These might be more southern, since most of my family has lived in the south for generations. Also some of these will be quite crude, as finnish people were and are absolute peasants :D)
"Iltatähti"
Lit. translation is "Evening star", however it also means the last child of a couple that's born considerably later than the couple's other children, usually born when the couple is quite old.
"Juosten kusten tehty"
Lit. Translation is "Made whilst running and peeing simultaneusly". It means that something was made in a great rush and suffered in quality because of it.
"Ei tuu lasta eikä paskaa"
Lit. Translation is "There won't be a child nor a log of shit born out of this" . It means that the finished product of what you are currently working on will be subpar/bad, or that it won't ever come to fruition.
"Pyörii ku puolukka perseessä"
or it's variation
"Pyörii ku hullun mulkku"
Lit. Translation of the first one "Goes around like a lingonberry in your ass", second one " Goes round and round like the dick of a lunatic". Both mean something is going in circles, literal or abstract.
I'll probably add more when I think of some good ones 