The term MANU is only used by Manchester United Football Club rivals as a complete and utter insult to the club and about the Munich air disaster which claimed the lives of eight players, especially Duncan edwards. The chants goes like
"Man U Man U went on a plane Man U Man U never came back again.."
The chants originally originated in 1960's when there was huge competition between clubs to sign Duncan Edwards in the early 50s to sign for a Midlands club, as he came from Dudley. His signing for United caused a lot of people in the Midlands to regard him as a traitor and was hate figure for them.
West bron fans first started the chants like "Duncan Edwards is manure, rotting in his grave,Man you are manure-rotting in your grave"
Liverpool fans often tease United about the Munich incident again by chanting ‘MUNICH -Man U Never Intended Coming Home.’
So all United fans, refrain from calling yourself MANU. United forever!!