Bullshit artist. Someone that constantly already knows anything you say before you say it and has already done it better, faster and harder than anyone else.
That guy is a bullshitticist. He always has to one-up everybody!
Paul: Why are you late?
Riley: It's my mum's fault. She's a cleaner who I've got to rely on for transport as I can't drive and don't have my driver's licence.
Paul: Enough with the bullshit! You're fired!