ltns
An acronym, long time no see.
Other variations include:
Long time no talk=LTNT
Long time no chat=LTNC
Long time no text=LTNT
Long time no speak=LTNS
Chatter #1: HEY! :D
Chatter #2: HYA! OMG! It's been forever!
Chatter #1: IKR, LTNS.