AND! a spare shoelace. You know that little leather shoelace thingey that attaches the strap to the neck of your guitar (unless you're one who defaces your guitar with a strap button on or near the heel)? Well, when it spontaneously says to itself "eight years, two months, three days, twenty-two hours, forty-six minutes, thirteen seconds and no more" you're potentially stuffed. Or having to resort to sitting down (shock, horror!) And it you're wearing slip-ons or velcroed shoes... (Luckily the foregoing was during rehearsal. Phew!)

--
Hamish