This is a video of Youtuber Moshe Tamssot using a McDonald's 'Create Your Taste' digital ordering kiosk to build the biggest burger possible. The system limits you to two quarter pound patties, but you can add up to 10x of all other ingredients (including three kinds of cheeses, bacon, guacamole, tomato, pickles, mushrooms, jalapenos, raw and grilled onions, and all the different sauces). So that's what he did. The burger came out to 3.8-pounds, and cost $24.89 (after a pricing bug in the system originally tried to charge $890.80). Unsurprisingly, Moshe hasn't released another video or been heard from since the incident.
Keep going for the video, then get out there and try to get your own heart to stop.
Thanks to chichi, who agrees the best thing on the menu at McDonald's is the reflection of the Taco Bell across the street.