Plot Hole v.1
Plot Holes are portions of a Plot that are missing and leave a break in consistence. For example: let's say that in a movie, everyone in the United States was bombed and immediately died. Now if later in the movie, the hero goes to the United States and it is a bustling utopia of ignorant pricks, gayness, and chronic masturbators, without telling how it got like that (Which actually happened to the United States, unbeknownst to the U.N.), it would be a Plot Hole. Plot holes will destroy us. Plot holes sucks.
The Demented Poopy-Saturated Llama went to the U.S. to eat cheese. He destroyed all the cheese in the world when he ate it all. THEN PEOPLE ATE CHEESE HA HA HA IT'S A CHEAP JOKE HA HA HA!!!
Usually Plot Holes happen when a main character [<--Backspace] [<--Backspace]
[<--Backspace] ... no more, that was factual! I deleted it all!
Then how is it still here? All you did was put <s> tags on it. That's a plot hole in itself. It would have been easier to actually delete them instead of just typing [<--Backspace]
Well, smart one, that was an example. How do you feel now Mr. Smart?
Plot Hole v.2
If a plot is so full of holes that it resembles swiss cheese, it will rip open a large hole in the Space-time continuum. The aptly named "Plot Hole" (the naming portion of the government was definitely not on the ball that day) then corrupts time and matter. Case in point: the year the movie (if you could call it a movie) The Big Empty came out, pandemonium broke loose all over the world, creating hurricanes and Bush's idea to run for President. It took all of two years to close that one. In the ninth season of Doctor Who, a plot hole of this kind created a bunch of weird flying creatures to kill all humans. Those creatures operate by a simple rule: The older something is, the stronger it is. Therefore, Grandpa is the strongest person in the world. Old people smell funny, so that means they all must have sandwiches for heads. It's such a fluent transition there, I don't even need to explain it.
(In)Famous Plot Holes
Unbeknownst to no one, because if everyone knew it would be another plot hole, the following are some famous holes full of plot. (For short, we call them "plot holes," although mundane people with no sense of plot or holes, especially not when put together, just call them Frank.)