redlining

Running a piece of equipment, most often an engine or other powerplant, way beyond it's rated maximum, usually in an emergency situation.

Usually, denoted by taking the engine revs or temperature up into the red area on an indicator dial, risking permanent damage or catastrophic failure.

In broadcasting or sound engineering, redlining is when the levels are set too high and the lines on the screen/board are in the red instead of the more desired orange or yellow. Leaving levels at this high level may cause your audio to sound distorted and unpleasant.

From redline -
Pronunciation: 'red-'lIn
Function : verb
: redline, to redline, also redlining; to engage in sexual intercourse at an extremely rapid tempo.

Origin in redline : a recommended safety limit; the fastest, farthest, or highest point or degree considered safe.

when a girl has her period.

A set amount of RPMs which your engine can put out before you pretty much blow it up. This is usually where your numbers on your tachometer start turning red, just be sure to keep it out of the red or else $$$$ will be needed. For instance, the redline on my 95 Jeep Grandcherokee is 5,300 RPMS that is exactly where they start turning red, some cars have a rev limiter on them, so due to my rev limiter the engine will not go past 5,300rpms and the engine starts "bouncing" meaning the needle will do the same. I advise you not to try this.

(noun, verb)

An informal sketch over another person's piece of art to point out and correct flaws, especially in anatomy. The sketch is usually in red.

When your car makes a funny noise to tell you that your need to shift gears or the engine will fucking explode