It's a sinister and fake laugh, much like one would hear from an evil villain. Obviously, there are few villains around today , other than employees of FOX "news", so when one types it today they are making fun of theirself. It beats the heck out of trying to make an emoticon to reflect the intent of whatever wickedly sarcastic thing they were saying.
"Penelope my dear, come down to the railroad tracks and help me look for flattened pennies. BUWAHAHAHA!!!" (If this was done in person then Penelope should decline the offer.)
by All-knowing-dude May 04, 2010