One person writes a random acronym (you can make up one if you want) and the person below it writes a phrase for it and then writes another acronym and so on...

Example:

randomperson123:

YOLO

Someoneelse:

You Only Love Oreos

LMAO

noneedforaname345:

Let Me Adore Orange

WTH

etc etc. Okay, I'll begin:

TTYL