Muna is a Finnish slang word for dick (as in penis). I was introduced to this word, in a rather unexpected fashion, through a demo (as in demoscene demo) by the Finnish group HiRMU called - quite simply - "Muna".
I swear I never expected that to be the theme of the demo -- nor did my friend, whom I wanted to introduce to the demoscene through it. The demo consisted of funky techno music, penises flying everywhere and a black "in-house model" who was standing with an erect penis and saying something (probably obscene) in Finnish. At least we both learned our first Finnish word that day.
P.S. "Muna", in Finnish, also means "egg" (as in: chicken egg).