Concerns about Prom

Okay, so my school has a Prom. (We're probably the only ones in Paris, but whatever.)

Prom is next Saturday at 10PM.

I do not have a dress. No prom dress, no regular dress, no dress PERIOD.

I NEVER wear dresses, because it's waaaaaaaaaaaaay out of my comfort zone. As is cleavage and bare legs and/or arms. I don't really want to spend money on something I'll wear once, so I was thinking of going in a tux. Is it acceptable?

I've held a poll among people I know: Yes: 4; No: 3; Double-check dress code: 1.

Help me please?