So bachelor in Finnish is just “boyman” (poikamies)? That’s hilarious. So you can say “Sä oot niin poikamies”. (“You’re such a boyman.”)
The apartment in which a single man lives is a poikamiesboksi, a boy man box.
Ah, but let’s not forget bachelorette: rather than being the logical tyttönainen (girl woman), it is poikamiestyttö (boy man girl).