9 up

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.

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!

9 up

9 up is slang in Hong Kong. How you write it in Chinese characters looks like this: 㞗/𨳊/鳩噏 (most Hong Kong people understand if you use 鳩 instead of 㞗 or 𨳊).
Meaning: To talk bullshit.
Explanation: The literal meaning of 㞗/𨳊/鳩 in Cantonese is "cock"/"dick". However in the slang, it means "stupid". 㞗/𨳊/鳩 sounds like 九 and the only difference is the tone. 九 means 9, which makes the first part of the slang. The pronunciation of 噏 sounds like the word "up" in English, and the meaning of the word is to state something. The word is usually used in the context of someone stating things that are not 100% true and without real proof.

These two words combined together = 9 up = to state something stupidly without real proof aka talking bullshit.

Cantonese:
香港人 A: 我為人講得出，做得到 我好信得過㗎！
香港人 B: 盲嘅都知你 9 up啦！成日都唔L做好你啲仆街嘢嘅，咪就係你條撚樣囉！
English translation:
Hong Konger A: Whenever I say I will do something, I will actually do as I say. I'm very trustable!
Hong Konger B: Even blind people know that's bullshit! The one who doesn't fucking do their god damn stuff, is you you dick face!