Here's how to get to this hidden game.
IPad only unless Android works the same.
Click at the top on "your trip advisor" then select "contributions"
Then, the game is to scroll down to the bottom and attempt to click on one of the links at the very bottom of the page, such as help centre, before the page auto scrolls up and you click on something else.
If it scrolls up and you scroll down again, then just before you press , it will auto fill many more contributions and whizz you up to the top again. It's just like that spoof on windows from the 90s where you had a window where you couldn't click on the x to close it because it moved away when the cursor went near it, but in a crappier and more accidental way.