OK, I just want to clear up the previous definition for an Electron Tube (the type used in guitar amps and high-end audio applications). The fella before me said tubes convert heat into electricity, this just goes to show that a little knowledge is a dangerous thing. Tubes do have a heater element, but this is seperate from any signal processing the tube performs. Tubes have anywhere from 3 to 5 elemets inside, not including the heater. The first is called a Plate, this is a metal plate with a given DC voltage applied to it, usually 200 to 400 volts. Another part is called the Cathode, this is connected to ground, sometimes through a resistor or capacitor network. The voltage "wants" to flow from the plate to the cathode, but between them is a "grid." The grid is connected to the input signal and as the signal changes from a positive charge to a negative charge (all musical signals are AC current, oscillating between + and -)it allows more or less of the plate voltage to flow to the cathode, resulting in a large voltage swing on the plate in time with the input signal: the amplified signal. The other elements go between the grid and the plate and serve to make the tube more efficient, these "screens" as well as the grid can be biased, that is, they have a fixed voltage applied to them to more carefully control how much current flows through the tube.
There is a heater element in the tube as well, very similar to a light bulb filament, but this only warms up the other components so that the tube can work better, this is analogous to putting oil in an engine. Tubes absolutely do not convert heat into electricity, I don't know if anything can convert heat into electricity unless you count a gas powered electrical generator, resistors convert electricity into heat, but that is another story.
Overbiased tubes will blow out because there is too much current flowing from the plate to the cathode, while under-biased tubes will have low output and sound thin, bitch.
by Nyquist Rocked June 6, 2006
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A water-pipe commonly referred to as a bong.
Often used by customers in glass shops because many shops are forced to not sell "bongs."

Tommy Chong associated the word "bong" with marijuana, so this has resulted in legal issues in some states. Tube was adopted as a more bong-like and shorter term than water-pipe.
"Let's rip tubes after class."

"Hey buddy, what are you looking for today?"- headshop employee
"A $300 bong"-customer
"You can't call it that. We don't sell bongs, only tubes/water-pipes."- employee
by truthin February 6, 2011
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The hair on the hose of a man's penis.
I can't say that I always trim my pubes but on the weekends I make sure to shave my tubes.
by kovstar July 11, 2008
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A secret doctors term for,
Totally Unnecessary Breast Examination.
Doctors convince patients to summit to a breast exam while they are there for something else.
"While your here mrs smith i'll give you a quick breast exam, pop your top off"

"Your not going to tube me you filthy old bastard"
by Anton bevermarsh January 10, 2021
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Something awesome, great, amazing, etc
Yo, did you see that comic that just came out? That shit is the Tubes!
by ImDocHolliday November 26, 2019
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As in "Google it," "Tube it" refers to look for something on YouTube.
#1: I'm looking for a demo on how to tie my shoelaces.

#2: Tube it. They've got everything on there.
by luapf May 11, 2010
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It is where you waste countless hours of your life searching for something good to watch.
I’m just going downstairs to do some tubeing.
by Quockey December 24, 2018
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