Normally, I would say "auf wiedersehen". But since what "auf wiedersehen" actually means is "till I see you again", and since I never wish to see you again, to you sir, I say good bye.
Vanalega myndi ég segja, auf wiedersehen en ūar sem auf wiedersehen ūũđir, sjáumst seinna og ūar sem ég vil ekki sjá ūig aftur, ūá segi ég viđ ūig, herra, vertu sæll.