Actually, the special plug is for the 220V European-style outlet by the desk which requires a compatible (type C) plug with two round pins. That noted, it probably does keep the hair dryers from disappearing as well.
Don’t just attach a two-pin Europlug adapter to a US specification plug to use that outlet unless the device being plugged in is 110-220V compatible. Many digital electronic device chargers are, but most US-purchased hair dryers are just 110V. Those may fry themselves rather quickly if they are plugged into the 220V outlet without a proper 220-to-110V voltage converter.