If you go to Google and search for [jokes] on mobile, Google will recommend you give the Google Assistant a try. At the top of the search results it will load a box that simulates the Google Assistant directly in Google search by sharing a joke with you right at the top of Google search.
No, Google won't show you a listing of joke web sites right away, first Google will show you their own jokes. I guess the big joke is on the sites that create jokes for a living?
Here is a GIF of it in action by try it yourself on mobile:
This was first spotted by AJ on Twitter.
This does not seem to do the same thing on desktop search, just mobile search.
Forum discussion at Twitter.
