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1. hdu
Text shorthand for "how dare you".
Person 1: "Yo mamma is fat."
Person 2: "HDU make a lame 'yo mamma' joke"
2. hdu
"short hand" for "How dare you?!"

How
Dare
U (short for "you" because we can't be bothered to write three letters anymore)
"HDU insult my mother's choices?!"
"HDU hate Britney Spears?!"

3. hdu
Text shorthand for "how do you"
"This homework is so hard like HDU even."
"HDU get up at 6AM on a Saturday, that's gross."
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