gnsg
Short for Good Night Sweet Girl. When texting a girl at bedtime and you don't have the courage to tell a girl the sweetest goodnight sentence of all time, you say this instead. She will reply with "huh?" and then you will text back a smiley. She'll find out sooner or later cause you'll cave and give it away. But the first few times you send it, it'll be your own little uber-romantic secret.
Dani: Ok, I'm going to bed. Night!
Zack: Gnsg.
Dani: huh?
Zack: :
Zack: Gnsg.
Dani: huh?
Zack: :