Truth or Dare strip poker, is played with much the same rules as standard strip poker, however in this version of the game losing all of your clothes doesn't mean you can't keep playing the game!
Once a person has lost all clothing, they continue playing their hands as normal. Whenever a totally nude player is required to lose an article of clothing, they instead subject themselves to a Truth or a Dare, administered by the player with the highest hand that round.
Traditionally, in Truth or Dare, the person performing the Dare, or answering the Truth gets to choose between Truth or Dare. You'll likely find a lot of players sticking to Truth if you go about it that way, though. One solution to this is not allowing players to choose the same option more than twice in a row (usually, but not always resulting in a truth-truth-dare-truth-truth-dare pattern) Another option is to shift the choice to the person doing the asking or daring (the winner of the hand).
Truth: A person owing a truth is asked a question by the winner of the hand, and is expected to answer truthfully. These questions are usually sexual in nature, but don't have to be, they are sometimes embarrassing, but in the spirit of the game, the loser should try to answer as truthfully (if not as completely) as possible.
Dare: As Truths, the winner administers these to whoever has no clothes, and is required by the game to remove something. Instead of a question, the player is asked (dared) to perform some action.
There may be times when a player will refuse to answer a question, or do a Dare (spoil-sports!). For these situations, have an alternate punishment for failing to live up to the Dare. If you and your friends are drinking, a shot of tequila can serve as punishment, and might loosen up that prudish player! If not, think of something all players agree on before hand.
Other possible punishments:
Jumping Jacks - Faced with a consequence of doing this nude in front of everyone may make the dare seem more appealing.
Frosty - The uncooperative player's underwear goes in the freezer for a while, and they have to wear them for a round after they come out.