This is the 7801st most frequent Swedish word.
ufo
Ufo: Unidentified flying object.
Here, 'ufo' refers to an unidentified flying object, which is the primary and conventional meaning of the word.
Jag såg ett ufo på natthimlen.
I saw a UFO in the night sky.
In this sentence, 'ufo' is used colloquially to describe someone acting in an odd or peculiar way, analogous to calling someone a 'weirdo'.
Han beter sig som ett ufo när han dansar.
He behaves like a weirdo when he dances.
This usage highlights 'ufo' as part of a broader topic discussing sightings and mysteries of unidentified flying objects.