So glad I finally asked.

She bakes, she blogs, she runs like me. And she knows stuff. So I eventually plucked up courage to ask Pierre about something that's bugged me for years. Which is this: how come, when you are riding the MTR or KCR, you sometimes see this odd little scene played out. Someone will be standing- there's no available seat- and another rises to leave the train at a station. The standing one may move over to the vacant seat and...stand there. Stand there. Stand there until after the doors have closed and the train has left the station. Then he or she will sit down. Somewhat gingerly.

What's up with that, Pierre, I said. Are they waiting to see if some infirm person or nursing mom gets on, so that they can hand over the jealously guarded seat to another needy citizen?

Nuh-uh, says Pierre.

Oh. Then are they worried about stumbling as they sit and ending up in the lap of the guy sitting adjacent? Are they waiting for the train to acclerate to a velocity more conducive to a stable touchdown?

No, dummy, Pierre tells me.

Nope, she says. What they are doing is waiting for the heat of the previous occupants arse to dissipate from the metal of the seat before they plant their own arse there. To sit down on another's heat, that would be unhygienic in some way.

I refer you to my blog, says Pierre. The arse is sacred.