I did find it amusing at the Middlesbrough FA Cup game to hear some young kids with some quite strong Leeds (I think?) accents in the away end in Brighton shirts.
I can believe that man u fans are unpleasant enough people to pull that on their own children, then find it funny and want to talk about it on the Internet.
Self awareness and not being a massive wanker are not features commonly associated with Man U fans.
By contrast, Brighton supporters are renowned throughout the land for our humour, charm and personal hygiene.