Ok, so you know the joke, "Instant human: just add coffee". You often find it printed on the side of a coffee mug, as a fun mug to have around the office. The joke clearly only works due to the extension of "Instant Coffee: just add hot water" that you often find printed on the label of a jar containing Instant Coffee.
Now one of my colleagues has a teapot that says "Instant Human: just add tea". In my mind this clearly cannot work as a joke as there is not, as far as I'm aware a company selling tea with the advice: "Instant Tea: just add water", so the basis for finding that joke surely doesn't work.
What's more is that some of my colleagues seem to find it funny, and when I explained the origin of the joke to them, they didn't understand and thought that it had nothing to do with the label on the coffee and that it was funny in it's own right. You can only truly appreciate the joke if you know the origin of it, otherwise it's like those situations where you enter a joke right at the end and laugh anyway despite not understanding what's funny.
What do you think? Is "Instant Human: just add tea" a joke in it's own right or not, and if it is, is it more funny if you know the original context of the joke upon which it is "based"?
Something to chew over, in addition to your lunch :)