I only just realized there are 22 pages to this thread. I haven't read them all. Maybe smaddy already gave the answer, but since you're still waiting for THE answer, I will give it here. Then you have to tell me why this answer works.
THE ANSWER
Ask either of the guards to tell you what the other guard would say.
For the second place prize, tell me why this would work.
If the guards are jamaican, you might here whichever guard you ask say:
He's LY'ON.