9 up is a slang used in Hong Kong. The way to write this slang is Chinese character is "鳩/𨳊/㞗噏" (Use "鳩" instead of "𨳊" or "㞗" because more people understand that, but using English characters "9 up" is still easiest to understand).
The meaning of the slang: to talk bullshit
Explanation: 鳩/𨳊/㞗's literal meaning is "cock" or "dick", but in different context it means different things. In this slang, it means "stupid" or "idiotic". This word in Cantonese (the language/Chinese dialect used in Hong Kong) sounds like 九 in Cantonese, and 九 means 9. This is why the first part of the slang is 9 which means "stupid" or "idiotic". For the second part of the slang, which is "噏", means to state something. The word "噏" is usually used with the context of people stating things that are not 100% true or without real proof. This word in Cantonese sounds like "up" in English, which is why the second part of the slang "up" means to state something not 100% true and without real proof. Combined together, it's to stupidly say something without real proof, aka talking bullshit.
The meaning of the slang: to talk bullshit
Explanation: 鳩/𨳊/㞗's literal meaning is "cock" or "dick", but in different context it means different things. In this slang, it means "stupid" or "idiotic". This word in Cantonese (the language/Chinese dialect used in Hong Kong) sounds like 九 in Cantonese, and 九 means 9. This is why the first part of the slang is 9 which means "stupid" or "idiotic". For the second part of the slang, which is "噏", means to state something. The word "噏" is usually used with the context of people stating things that are not 100% true or without real proof. This word in Cantonese sounds like "up" in English, which is why the second part of the slang "up" means to state something not 100% true and without real proof. Combined together, it's to stupidly say something without real proof, aka talking bullshit.
Cantonese:
香港人 A: 我為人好守信用㗎！我凡事都講得出，做得到
香港人 B: 盲嘅都知你喺度 9 up 啦！成日唔L做好D仆街嘢嘅，咪就係你條撚樣囉！
English translation:
Hong Konger A: I'm a very trustable person! Whatever I say that I would do, I would actually do it no matter what it is.
Hong Konger B: Even blind people know that you're talking bullshit! The one who never fucking does his god damn stuff ,is you! You dick face!
香港人 A: 我為人好守信用㗎！我凡事都講得出，做得到
香港人 B: 盲嘅都知你喺度 9 up 啦！成日唔L做好D仆街嘢嘅，咪就係你條撚樣囉！
English translation:
Hong Konger A: I'm a very trustable person! Whatever I say that I would do, I would actually do it no matter what it is.
Hong Konger B: Even blind people know that you're talking bullshit! The one who never fucking does his god damn stuff ,is you! You dick face!
by blackbuilder7145 May 23, 2022
Get the 9 upmug. Josiah stocked up on eggnog to get nogged up in the summer.
Johnmark nogged up the FDA to approve drinking eggnog year round.
I nogged up Michael to help with my taxes.
Johnmark nogged up the FDA to approve drinking eggnog year round.
I nogged up Michael to help with my taxes.
by Michael Jinglebells December 30, 2019
Get the Nogged Upmug. Means that i am the best
by 👍🔥 August 6, 2022
Get the Thumbs upmug. 
by beanbrownnies April 16, 2022
Get the 4 fingers upmug. by Hmm nice October 8, 2022
Get the 4 fingers upmug. what in the gen z
🎋 yo 🎎 what 😢 is 👨 🦰 up 🤴 you 🤴 Guys 👌 right 😎 now 🙎 ♂️ we 🤡 are 😛 at 👹 McDonalds 😡 and 👨 🔧 we 🩱 just 😏 found 🤗 out 🎨 when🎗 you 👨 🦰 come 👨 🦳 to 🎅 McDonalds 💤 at ☦ 3AM ☺ you 🥶 can 🎟 get 🎢 the 👝 Among 🩱 us 👩 🎨 Happy 👨 🔧 Meal 🦗
by burn your fat November 25, 2024
Get the 🎋 yo 🎎 what 😢 is 👨 🦰 up 🤴 you 🤴 Guys 👌 right 😎 now 🙎 ♂️ we 🤡 are 😛 at 👹 McDonalds 😡 and 👨 🔧 we 🩱 just 😏 found 🤗 out 🎨 when🎗 you 👨 🦰 come 👨 🦳 to 🎅 McDonalds 💤 at ☦ 3AM ☺ you 🥶 can 🎟 get 🎢 the 👝 Among 🩱 us 👩 🎨 Happy 👨 🔧 Meal 🦗mug.