If Superman is basically a stronger, more flight-enabled version of a regular man, then a supercell is basically a stronger, more tornado-enabled version of a regular storm cell. This is because—much like tornadoes—supercells have the tendency to spin around a lot, but also—and more importantly—because supercells can actually create tornadoes.
In case it needed to be mentioned, supercells are the most dangerous of the four major storm types, in addition to being the scariest to look at. Thankfully, they’re also the most rare, and tend to be confined to the central United States during the springtime. If you ever happen to come across one, wherever you are, just remember the advice you got: move in the other direction.