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1.
"Sitting In My Chair Laughing" This acronym relpaces 'ROFL'. because honestly who's really going to roll on the floor from laughter?
Stewie Griffin: Hey Brian! Brian!
Brian Griffin: What?
Stewie Griffin: Knock-knock
Brian Griffin: sigh Who's there?
Stewie Griffin: Your friend, Stewie. And he's always gonna be there for you!
{SIMCL}
by Alex/Jackie|Jackie/Alex July 28, 2008
 
2.
SIMCL is an internet acronym for Sitting In My Chair Laughing. A variant on the acronym "ROFL". SIMCL has been hailed as the more realistic description of what someone is actually doing when they use the term ROFL, that is, they are most likely not rolling on the floor and typing at the same time but sitting in their chair and laughing.
Michael: If I was king where do you think I should keep my armies?

John: In your sleevies.

Michael: simcl.
by AMNotAlone August 10, 2010