Electromyography

An EMG- a procedure to assess the health of muscles and the nerve cells that control them
Also known as the most painful procedure known to man, where student nurses stick you with needles then proceed to pulse electricity down through the needles to see how your muscles react to the 'stimulation'. Often this causes extreme pain, as it aims to target nerves and the way they control the muscles.

Person 1: Shit dude that's gotta hurt like a b*tch
Person 2: Hurts like f*uck but its nothing on an Electromyography
Person 1: The f*ck is that?
Person 2: An EMG, the Satan's own invention sent to the medical industry.