fwm

"Filled With Mirth"

mirth/mərTH/
Noun:
Amusement, esp. as expressed in laughter.

To replace the short hand "LOL" and "haha"

Jim- "Why does the seagull fly over the sea?"

Sally- "IDK, Y?"

Jim-"Because if it flew over the bay it would be called a bagel."

Sally- "FWM!"