Funny you should mention it, Walrus. I was standing in a coffee queue on campus a while ago and a young lady (whom I'd never seen before) behind me was wearing a T shirt with "PLACEBO" across it, strategically. Not realising it was the name of a band (ah, such ignorance!) I thought about the word for a while and then asked her, "Do they have the same effect as the real thing?"

She didn't immediately realise what I was referring to but, when I pointed to the word, she got the joke and laughed. A few days later I was in the coffee queue again and she was working behind the counter making the coffee; she told me she'd told a friend of hers about my comment and the friend had immediately said, "Oh, that must have been Rowan!" So I 'fessed up' and introduced myself, marvelling at network theory; I was amazed I could be so easily identified.

Still in the queue I then told her about the Ag Science student (another young lady) I'd once taught who was wearing a T shirt with a provocative comment about sowing wild oats; I suggested to her that she keep a good supply of Roundup (a popular weedkiller here) but the student hadn't a clue what I'd meant. The coffee maker did though; she wasn't green, just young.

Cheers, Rowan