Books usually don't do it, although we had a thing going with the Dragon Mountain boxed set in the past. What really works is any unexpected question asking for more details about the PCs action, asked innocently:
Where exactly where you standing? Where you leaning against the wall, not touching the wall, or somewhere in between?
What did you say after you picked up that black book? Could you repeat is to me slowly, word for word.
Did you touch the green liquid with your weapon or with your hand. And what material is your weapon made of, or your gauntlets or gloves for that matter. You don't wear any gloves? Really?
Were you standing at the rear of the group? How much space between you and the guy before you? Ten feet? Are you absolutely sure?
Just not knowing what the right answer to these questions should be really freaks them out. And I often ask these question for no reason, just to keep them on their toes.
But in a pinch I pull out the Psionics Handbook. Since psionic characters are not allowed in my campaign, and nobody owns the book. They fear the unknown.