Pocketdrum

Pocketdrum (n.) is the short burst of percussion you perform on your own body in the doorway, half a second before you step outside. Left trouser pocket: keys. The right one: phone. The chest, or somewhere inside the coat: wallet. Three taps, sometimes four, always in the same order, and always with a good deal more force than is needed to detect a set of keys.

Everybody has a pocketdrum and almost nobody chose theirs. It assembles itself out of whatever you have most recently lost. Leave your keys on a kitchen table once, in the rain, with a taxi waiting, and the key beat becomes the first and heaviest note for the rest of your life. The rhythm is personal and remarkably stable. You have probably been playing the same four beats since your twenties.

The pocketdrum is not really about the pockets. It is about the door. Doors that lock behind you produce the loudest and most elaborate drumming; a door you can simply push open again barely earns a tap. Hotel rooms are the worst offenders, since the pockets are unfamiliar, the door is merciless, and there is a plastic card in the game that feels like nothing at all.

There are established variations. The two-handed pocketdrum, played symmetrically, favoured by people in coats with more pockets than they can name. The walking pocketdrum, performed while already halfway down the path, which sounds far more confident than it is. And the ghost pocketdrum, played at eleven at night on a dressing gown that has no pockets whatsoever, purely because the hands had nothing else planned.

It has failure modes. The false positive, in which a wad of old receipts produces a satisfying key-shaped lump and sends you cheerfully out to a locked door. The double drum, where you finish the sequence, take two steps, and immediately play the whole thing again, having somehow failed to record the result of a performance you gave four seconds ago.

There is also a social use. The pocketdrum played at a restaurant table, loudly and with both hands, announces that you are leaving without anybody having to say the word leaving. Coats are fetched. An entire evening is ended by percussion.

Underneath the comedy sits a real and slightly fragile piece of mental machinery. Psychologists call it prospective memory: remembering to do something in the future, rather than recalling a fact from the past. It is the memory that reminds you to take the letter with you and to pick up milk on the way home, and it is easily crowded out by whatever else is going on at the time, which is why the doorway, of all places, is where it tends to fail.

The tapping is the honest answer to that. A memory that you put the keys in that pocket feels exactly the same whether it belongs to this morning or to last Tuesday, because you do the same thing every day and the days blur into one another. A hand pressed against the actual lump of metal is not a memory at all. It is evidence. The pocketdrum is the shortest experiment anybody ever runs, conducted in a doorway, by a person who has learned, slowly and expensively, not to take their own word for it.