Enchantment, U (1) Each player reveals the top card of his or her library to all other players by continuously holding it against his or her forehead. This does not allow a player to look at his or her own card. (That card still counts as the top card of your library. Whenever you draw a card, draw that one and replace it with the next card of your library.)1
Illus. Claymore J. Flapdoodle
This card is hard to play with when Handcuffs is affecting you. [Barclay 1998/08/13]
You may tell an opponent (not a teammate) what their card is. You may also lie about this. [Barclay 1998/08/13]
Licking your card or using sweat on your forehead to stick it is legal. [QAS 1998/09/09] But you have to be careful about marking the card.
Balancing the card on your glasses or sticking it in the strap of a backwards worn baseball cap also works. [QAS 1998/09/09]
If there is a mirror (or similar object) such that a player can see their own card, they must reorient themselves or cover the mirror. [D'Angelo 1999/02/21] Vampires are exempt from this rule. [Dracula]
All tournament formats have banned cards from Unglued.
Unglued
(Rare)