'Outsider'. Some foreigners wear it knowingly; be sure you're one of them.

What a Japanese person actually thinks
Reads as a deliberate statement, which it has to be. Some Japanese people will find it funny and self-aware; others will find it uncomfortable that you're wearing a word they've been told not to use.

Meaning

Literally: outside + person
Actually: Foreigner — a clipped form of 外国人 that many people consider mildly rude, precisely because it says 'outsider' rather than 'person from another country'.

Scores

Naturalness●●●●●

Correct and extremely common in speech, with an ongoing debate about whether it's impolite.

Coolness●●●●●

Works only as knowing irony. As a sincere identity statement it lands badly.

Watch out

mediumJapanese media guidelines generally prefer 外国人. Wearing the clipped form makes a point whether you intend one or not.

On skin

外人

Orientation: either

Brush, if the irony is the plan.