Or when the UK decimalized the pound.
For folks used to thinking in shillings and pence, the newpence was a pretty jarring idea. Which doubtless felt to them like prices were rendered as “X[familiar units].Y[unfamiliar units]”.
From the “yard of ale” scene on Peep Show:
Jeremy Usborne: What can I get you two? How about a foot of wine?
Lucy: Can I get a metre of vodka…
[to Mark, with a flirty look]
Lucy: with an inch of tonic?
Mark Corrigan: [voiceover] Come on, Mark! Turn it on, play the game!
[to Lucy]
Mark Corrigan: Oh, uh, naughty, you’ve combined metric and imperial, you might get an interdenominational… you know, from mixing the two measurement systems, a hangover of that kind.
[voiceover]
Mark Corrigan: Just stay mute, Mark. You’re a social freak. Remain in your compound.