It's hard to pinpoint when I became the person who says "shush", as opposed to being the person who is regularly told to shut up. I remember at school Mr Price called me a "horrible little squirt" because I talked too much, so it was definitely after that. It also postdated the incident at a friend's house in 1991 when her father exploded in fury at my relentlessly inane blathering and we had to leave the building while he calmed down.
But since then I've developed a mental allergy to people all talking at once or too loudly, along with a habit of saying "shush". Although I do stop short of saying "shush" while placing a single finger on the lips of the person who I wish would be quiet, because it doesn't pan out like it does in the movies. The other person tells you to get off. Quite loudly, in fact. It achieves the precise opposite of what you want, like when you chuck a bucket of water on a chip-pan fire and then say, "Oh blimey."
Extraneous noise now drives me nuts. Last week I sat in a Georgian restaurant – we're talking cuisine from the former Soviet republic, here, rather than 1750s Britain – and I couldn't hear what a friend was telling me about some romantic liaison she was embarking on because patriotic songs of the Caucasus were playing over a small PA system and drowning her out.
In these situations I tend to zone out as speech and muzak combine to form an unprocessable lump of audio data; I just gaze into the middle distance, sighing. It turned out she was after some advice, which I eventually gave, but I don't think she took any notice of it, which is probably just as well, because asking me for that kind of advice is like asking me to help defuse a land mine.
Maybe it's conditioning. After all, I spend most days working alone in silence, punctuated only with birdsong and sirens of ambulances carrying people suffering multiple fractures to the A&E department of the hospital next door. Or maybe it's a well-documented precursor to some kind of brain disease – but if that's the case, please don't write and tell me. I'd rather live in ignorance, and then die as someone asks me if I'm sure I'm all right, and I just reply, "shush."