Remitent of a Strong bad mail and abreviation of "fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf". This was probably just random typing; many letters in this name are next to each other on a typical English-language QWERTY keyboard. In attempting to reply, Strong Bad shortened the unwieldy name to "fhqwhgads".
Later that year, he wrote a song about it and The Cheat created a music video about fhqwhgads, "Everybody to the Limit". The song is later featured in the game Dancin' Bubs.
Contrary to popular belief, Strongbad, as awesome as he is, did not invent the word fhqwhgads. The SB email in question was a reference to the famous I love you virus that caused the destruction of many PCs. The I love you virus was exactly as shown in the SB email:
*two people playing hangman*
*one person loses*
The winning person: the word was Fhqwhgads
the losing person: that's not a real word the winning person: actually, it is, because it is