Used to refer to Harley-Davidson.
Harley-Davidson likes to refer to itself as "The Motor Company", which, over the years, often got shorted to "the MoCo".
Since "Mofo" already was part of common vernacular, Redbeard Emeritus came up with "the MoFoMoCo moniker in the rec.motorcycles.harley Usenet newsgroup in the 90s.
"I tried to get this blown up engine covered by the warranty, but the MoFoMoCo denied it."