Japan's prime minister Shinzo Abe emerged from a warp pipe at the Rio Olympics dressed as Mario. You have read that sentence correctly.
The stunt was part of the closing ceremonies during the portion where the host nation for the next Olympics is introduced. The 2020 Olympics will be in Tokyo.. Abe wore a red Mario cap and was briefly clothed in Mario's overalls, which fell away. (He had a suit on underneath. Don't worry, this was weird, but not that weird.)
You have to watch the video excerpt at NBC's YouTube channel; we've included the screenshot above.
(Disclaimer: NBCUniversal is a major investor in Vox Media, which owns Polygon)