While in London promoting Trolls, hilarity ensued when Timberlake and Kendrick were tasked with lighting up the London Eye, that giant behemoth of a ferris wheel that towers above the Thames. The point of the stunt was to turn the London Eye into one rainbow-hued, lit-up marvel, but it became very clear very quickly that those true colors (#jokes) weren't playing nice with their circuitry.
How many famous people does it take to light up a ferris wheel? More than two, apparently! Turns out if you make a very goofy face to go with the very serious action of pushing a cartoonishly large button as your hit single from your movie's soundtrack blasts in the background, it won't do you any favors when it comes to the task at hand.
Eventually, the London Eye lit up with a colorful glow, and an embarrassed member of the production crew ran up to the stage and grabbed the offending button and its podium. No harm no foul, but JT and Anna, it's probably best to stick to the script and avoid electronics at the next press junket.