If you are going to fling a pie at some rich pig as a way of publicly taking them down a peg, the preferred, and traditional, pie is a cream pie, but you should include both a crust and a filling, even if the latter is just whipped cream (kind of lame).
That being said, I do not approve of the actions of comedian and political activist Jonathan “Jonnie Marbles” May-Bowles, who flung a pie tin full of shaving cream at Rupert Murdoch when he was testifying before Parliament. (His wife deflected the projectile, that’s love … and good reflexes)
Mr. May-Bowles, if you are to fling a pie at Rupert Murdoch, make it a real pie.