Head Loss is defined as:
1. To move a given volume of liquid through a pipe requires a certain amount of energy. An energy or pressure difference must exist to cause the liquid to move. A portion of that energy is lost to the resistance to flow. This resistance to flow is called head loss due to friction.

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2. When she doesn't finish sucking on yo dick when she be giving you a blowjob so now you have blue balls which sucks.
Katherine couldn't fucking finish me out last night and now I have a serious case of head loss. My balls are 'bout to explode from the pain. *Thinks to self* "FUCKING SWALLOW YOU BITCH."
by Hilarious Highschooler May 26, 2016
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When you are angry you are a head loss.
"Emily stop acting like a weirdo, you are a head loss"
by Cheglin January 2, 2023
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