Y

From Fancyclopedia 2, ca. 1959

Because some scribes of Norman England didn't know enuf about Anglo-Saxon to continue spelling words like "hwaet" with an hw, but instead spelled them wh, the h element has almost disappeared in recent-immigrant-dominated regions of the US like the Atlantic seaboard, and Y and "why?" are pronounced identically. Hence such puns as YFanac.

From Fancyclopedia 1, ca. 1944

Because some scribes of Norman England didn't know enuf about Anglo-Saxon to continue spelling words like "hwaet" with a hw, but instead spelled them wh, the h element has almost disappeared in recentimmigrant-dominated regions of the US like the Atlantic seaboard, and Y and "why?" are pronounced identically. Hence such organizations as the YIAOPUMUMSTFPUSA, Unltd.