Fergie can be used as a verb, an adverb, an adjective or a noun. It can mean whatever you like without the person you are saying it to really know what's going on
'I'll Fergie you up!!!'
'Don't make me Fergie you tomorrow...'
'Let's go to Fergie sometime...'
'I will literally Fergie him right up the bum
He ran Fergilly down the park