ROFLOTI
Rolling On the Floor Laughing On The Inside. This is derived from the classic ROFL acronym. It is often used as a defense mechanism to when someone is called out for not actually ROFL'ing after they claim to be.
Dude1: (gives a joke punchline over IM)
Dude2: ROFL!
Dude1: you're not ROFL, I can see you.
Dude2: ROFLOTI
Dude1: Ok, that's better.
Dude2: ROFL!
Dude1: you're not ROFL, I can see you.
Dude2: ROFLOTI
Dude1: Ok, that's better.