Asking for water as a means of tricking him, then try to knock him out.

You decide that tonight is the best time to try and break out of here. You give the guard your best seductive look and ask with a melodious voice, "Could I have some water then?"

As he goes to fetch the water you prepare yourself. If you can knock him out quickly he might have the key and your chance of escape.

He returns and enters the cell. He is tall, handsome and very well built, but you have no time for such things.

"Here you go," he says looking you over carefully.

"Could you help me?" you innocently ask, "I can't really drink because of these chains."

As he draws closer, you wait and then pounce.

Quickly you lash out with the strongest front kick you can muster aimed for his groin.