Outre things are eccentric or shockingly strange. Your outre outfit might be fine to wear to a Halloween party but less appropriate for a job interview.
The adjective outre is often spelled with its French accent: outré. In French, this word means "exaggerated, excessive, or extreme," and is a past participle of the verb outrer, "to carry to excess or overdo," from outre, "beyond." If something is beyond what's considered normal or ordinary, it's outre: "His one-man play was so bizarrely outre that the audience didn't know how to respond."