One of our question writers put on a jacket, and put his keys into the righthand pocket. Later in the day he took off the jacket, leaving the keys in the pocket, and hung the jacket on a peg.
The following day he took the jacket off the peg and put it on. The keys were now in the lefthand pocket. At no point since putting the keys in the righthand pocket had he touched them.
What characteristic does the jacket have?
The jacket is double-sided. Before putting on the jacket for the second time he turned it "inside out" and wore it with the other side showing.