Coupon is TESTANDCODE
I had already used it before realising it was one or the other, honestly its one of the better TLD’s IMO, too bad Cloudflare doesn’t support it yet.
Edit: I should have mentioned, you have to make a tentative payment of 1 USD, which is reverted.
They don’t yet support these TLDs, but according to this blog post they will be added very soon:
Given its a 60 day wait anyway, that sounds good.