Light Emitting Diodes, like any diode, have extremely high resistance to current flow in one direction and much lower resistance in the other direction: they only light up when they're connected in the correct polarity.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>