Haven't thought of any yet, but here's one from Flann's Catechism that could be directed at the psychics:
In what can no man tell the future has for us?
Or, directed at a certain psychic who floods this forum with her nonsense:
In what direction should I shut?
Funny enough, she lives in Dalkey. What an amazing coincidence, eh?
Thanks for the link, Your Lordship. Flann O'Brien, mighty indeed! Please, everyone, if you haven't already, read The Third Policeman.