Anatidaephobia
The fear that somewhere, somehow, a duck is watching you.
Bling, Bling
[see Ali G]
Chrono-synclastic infundibulum
A place in time and space where different, yet entirely valid, understandings meet - there by determining a more accurate portrayal of reality. [see Vonnegut, Kurt]
Mu
A Chinese word meaning "not yes, not no" or "this does not have any meaning." It could be the answer to the Zen koan, "Does a dog have the Buddha nature."
Ohmigod
(Usually in reference to Kenny) [see Southpark]
Vela
consellation and supernova remnants

The Washington Post published a contest for readers in which they were asked to supply alternate meanings for various words. The following were some of the winning entries:

Abdicate
(v.), to give up all hope of ever having a flat stomach.
Carcinoma
(n.), a valley in California, notable for its heavy smog.
Esplanade
(v.), to attempt an explanation while drunk.
Willy-nilly
(adj.), impotent
Flabbergasted
(adj.), appalled over how much weight you have gained.
Negligent
(adj.), describes a condition in which you absentmindedly answer the door in your nightie.
Lymph
(v.), to walk with a lisp.
Gargoyle
(n.), an olive-flavored mouthwash.
Bustard
(n.), a very rude Metrobus driver.
Coffee
(n.), a person who is coughed upon.
Flatulence
(n.), the emergency vehicle that picks you up after you are run over by a steamroller.
Balderdash
(n.), a rapidly receding hairline.
Testicle
(n.), a humorous question on an exam.
Semantics
(n.), pranks conducted by young men studying for the priesthood, including such things as gluing the pages of the priest's prayer book together just before vespers.
Rectitude
(n.), the formal, dignified demeanor assumed by a proctologist immediately before he examines you.
Marionettes
(n.), residents of Washington DC who have been jerked around by the mayor.
Oyster
(n.), a person who sprinkles his conversation with Yiddish expressions.
Circumvent
(n.), the opening in the front of boxer shorts.
Frisbatarianism
(n.), The belief that, when you die, your soul goes up on the roof and gets stuck there.

The Washington Post's Style Invitational also asked readers to take any word from the dictionary, alter it by adding, subtracting or changing one letter, and supply a new definition. Here are some recent winners:

Sarchasm
The gulf between the author of ironic wit and the reader who doesn't get it.
Reintarnation
Coming back to life as a hillbilly.
Giraffiti
Vandalism spray-painted very high.
Foreploy
Any misrepresentation about yourself for the purpose of obtaining sex.
Inoculatte
To take coffee intravenously.
Osteopornosis
A degenerate disease.
Karmageddon
It's like, when everybody is sending off all these really bad vibes, right? And then, like, the Earth explodes and it's like a serious bummer.
Glibido
All talk and no action.
Dopeler effect
The tendency of stupid ideas to seem smarter when they come at you rapidly.
Intaxication
Euphoria at getting a refund from the IRS, which lasts until you realize it was your money to start with.
Ignoranus
A person who's both stupid and an asshole.