Heya. Swede with Finnish parents here. I understand “general” Finnish or at least follow the gist and I can sorta speak but my writing is terrible, hence this question in English.

I heard on the Swedish news a Sverigefinne use the term “kuivaa läppää” that I’ve never heard before.

Dry… flap?

I got it that it means approximately “unfunny” or “joke in bad taste”, but my wonders - what kind of flap? And why is it dry?

I’m trying to keep my mental image clean but I’m struggling here.