Penn & Teller are Penntium "Penn" Jilette and Teller "Teller" Teller -- magicians specializing in comedy, weirdness, skepticism, eccentricity, annoying thin-skinned magicians, and occasionally freaking the heck out of people. Penn is an ex-circus fire-eater and cousin of the late Andre the Giant who has one fignernail that thinks it's a girl. Teller, a one-time philosophy professor, believes that everything that needs to be said has been said and therefore does not speak unless spoken to (and Penn never speaks to him).
P&T have appeared on many television shows, starred in a movie, and have their own television series, Bullish!, in which they talk about things they are really "bullish" on.
The pair is famous for oddball effects such as locating a card by stabbing someone in the chest, locating a card through drowning, locating a card by being devoured by angry rats, locating a card with a disembodied monkey head, and dumping a cargo container full of cockroaches on an unsuspecting David Letterman. Some magicians disapprove of P&T because the duo sometimes performs effects in a way that might make it easier for spectators to figure out how the trick is done (such as performing a sawing-someone-in-half routine using a clear plastic box).
Currently, we do not have any Penn & Teller tricks to expose, because they've pretty much exposed them all themselves.