ROFLTSO is an internet acronmym for Rolling On Floor Laughing, Tongue Sticking Out. It's an overjoy laugh while tongue is sticking out, teasing, making fun of or joking around.
Jimmy; Hey! Why did the chicken cross the road?
Ryan; I don't need to know....because it's ROFLTIME!
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Jimmy later switched to geico, saving a bundle on car insurance.
Related to ROFL, a ROFLASM means both to laugh so hard it comes close to orgasmic in its quality, and also literally abbreviates the phrase 'Roll on the floor laughing and shat myself'.