We have decided to do something a bit more creative for April Fool's Day this year, rather than just another joke (note the 4th link). This year, we have an actual activity that you can get involved in! There will of course be a joke involved, but we'll get to that later.
If it goes well, we will consider making this an annual event (or at least a somewhat regular event). It will hopefully encourage people to discover artwork that they might not have actually seen before and offer a chance to look back at those pieces they've already seen.
What the activity is:
We have hidden a relatively well-known joke somewhere within a gallery piece, your mission if you choose to accept, is to find the correct "answer" to this joke. It's extremely likely that you will know the answer when you see it, but the tricky part is finding it. (Remember, if you work out the code it should be far less difficult)
The first one to find the answer will get a gold star and obviously bragging rights too! If you think you've found it, leave a message in the comment section with the answer. The competition will close once the joke's answer has been found. Good luck, puzzle solvers!