In one of my last games, I offered a draw. Now for what the rules don't say...
He had quite to chew on the offer. Half an hour he was sitting and pondered whether he could risk to play to win. I, on the other cheek, always have ants in my pants. Technically, there would be nothing wrong with just walking away - it's not my move, the draw offer is marked on both our sheets, he could stop the clock and either wait for me to come back or hand in the result. But I found walking a bit impolite.
Thus: "Sitting on the dock of the bay" or "Runaround Sue"?