Custom motorcycles are nothing new, but you rarely see a tuning shop build one around a car engine, that is unless...you're talking about "The Mad Boxer". Powered by a Subaru WRX 2.5L turbocharged boxer engine, many of the bike's parts were custom built and CNC-milled by the owner, Marcel van Hooijdonk, himself. Other mods include: a Kawasaki fuel tank, Japanese 2-speed automatic transmission, a turbo swap that replaces the WRX original, and Buell brakes. Click here to view the first image in today's viral picture gallery. Continue reading for the five most popular viral videos today, including one showing how to survive the apocalypse.