PC.net

G9

Meaning Goodnight
Type Abbreviation
Rank ★ ★ ★  Common
Usage Online Only (chat, messaging, e-mail)
Comments

G9 is a simple way to say goodnight in a text message or online chat session.

Updated November 19, 2009
Meaning Genius
Type Abbreviation
Rank ★ ★ ☆  Average
Usage General (not just online)
Comments

G9 is also short for "genius," a really smart person.

Updated November 19, 2009
Information from PC.net
https://pc.net/slang/meaning/g9
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