"If someone put a gun to your head and make you choose between Obama and Romney, what would you do?" "I'd take the bullet."
Seriously, though, I had the same situation in 1992. I could not stomach Bush, Clinton OR Perot (after he dropped out with that idiot-level excuse). I heard the LP candidate was a turkey, but I voted for him, anyway, feeling that I could at least help the Libertarian Party with ballot access in the next election.
I believe voting Gary Johnson is the best alternative. However, if you cannot bring yourself to do that, write in Ron Paul. It cannot hurt, even if it does not count. I would even make that suggestion to Oklahomans, if they have access to a paper ballot. Otherwise, you might as well abandon the ballot box for the cartridge box and get it over with.