“What the must” is a phrase to use when you are grossed out or confused.
A way to use “what the must “ is as followed,

Friend 1: “Look at Mr.Bills balls, I bet they are so hot and hairy.”
Friend 2: “That is so gross, what the must.”
by Justin205 February 14, 2022
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Do what you feel is best, what makes you happy. You do you! (A relatively new piece of South African slang)
*Tristan asks what colour he should choose*
Morgan replies, "Dala what you must!"
by TADPOOL September 6, 2016
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Is a South African phrase which means, "do what you must". "Dala" is a Zulu word which means to cause, do or create.

It is commonly used during confrontations wherein a mofo is testing your G and you propose escalating matters to whatever levels they deem necessary; be it physical or otherwise.
Tom: I'm really get tired of sh*t Thabo.
Thabo: Then dala what you must, I'm not scared of you.
by Zipho September 17, 2019
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It means exactly what it seems. A simple and common proverbial phrase, arguing what goes up must come down.

The example below is an except from 'Human Traffic' (1998), an independent British film said by character Jib.
What goes up must come down, and down, and down. Everyone looks ill at the end of the night. All have lost the power of speech, desperately avoiding eye contact. Your new soulmate, that you have been talking cod shit to for the past five hours about the story of creation or the fourth Star Wars film, is now a complete stranger.
by ArousedPopeye January 13, 2015
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A rude phrase used in response to irrelevant information that has been brought to your attention and has no value to your life whatsoever. Most likely annoying
Sunny: “I was on FaceTime with ”

Jack: “Okay now what must cut?”
by Miyagison January 9, 2022
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