Foo Fighters 

1. An amazing band.
2. A mysterious ball of light that followed WW2 US planes sometimes know as "Kraut Balls", they were attributed to Japan, but could be of extra-terrrestrial origin

1. Nate Mendel in the Foo Fighters is an amazing bassist
2. Aghh! There are foo fighters all around the plane. We are doomed!

Foo Fighters by Tom Brownlee July 29, 2003

foo bar 

foo bar is very often used in computer programming, used to declare a (temporary) variable.
Most probably, "foo" and "bar" came from "foobar," which in turn had its origins in the military slang acronym FUBAR. The most common rendition is "Fucked Up Beyond All Recognition"

Suppose we have a function named bar and a variable foo. To call the function we use foo bar.

foo bar by Dave August 2, 2006

ass foo 

Term used as a compliment. Also a way to talk to friends.

"Sup ass foo"
"Trippin ass foo"

ass foo by CatMan357 October 21, 2013

web foo 

The skills of an elite Web Developer/Designer

"Man, that guy has some serious web foo going on."

"That dude has got some crazy web foo skills"

web foo by Mark G. July 10, 2005

Foo Fighters 

1) Unidentified lights in the night sky in WWII seen by some American fliers over the Pacific Ocean and Germany at night. "Foo" comes from a comic by Bill Holman. Not fully explained, but most likely a result of "Aviator's Vertigo."

2) A great, though uneven, rock band fronted by Dave Grohl, who may be the coolest thing that has ever been.

When flying over the Atlantic, Dave Grohl reportedly saw some foo fighters, and said "cool." Then he went back to sleep to dream about how cool he is.

Foo Fighters by LudwigWittgenstein May 4, 2009

Foo Fighters 

Fantastic band!

Those Foo Fighters are really a fantastic band.

Foo Fighters by Myself May 29, 2003

foo clad 

Another way of saying too bad

It originated from an episode of "Even Stevens" when Louis' crazy uncle comes to town causing trouble.

The scene where the phrase "foo clad" takes place when Louis got into an argument with his dad because he was supposed to be washing the car but instead hung out with his crazy uncle.

Louis: Well too bad.
Steve: What did you say?
Louis: I said...foo...clad.
Steve: FOO CLAD!?

foo clad by Louis Stevens March 25, 2009