xkcd #3232: Countdown Standard
Title text:
Anyone who is caught counting ‘three … two … one … zero … GO!’ will be punished with a lifetime of eating only ISO standard food samples.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3232/
I’m genuinely surprised it’s not mentioned in the hover text … though I think you can see it in between the lines there.