Host Jeff "JJ" Johnson highlights the Boston University Bridge. He also explores why the U.S. uses 120 volts instead of 240, whether swimmers really need to wait an hour before swimming after a meal, how birds sleep standing up, how the gun worm became a corkscrew, how D-Day and Bluetooth got their names, how dry cleaning works, and the invention of bifocals. Part of the "Wow! I Never Knew That!" series.