Used to express laughter that is not necessarily funny to everyone around, but makes one laugh on the inside.
This type of laughter can also be found when one laughs at an inside joke expressed over a text where laughter cannot necessarily be heard.
"Do you remember your DISNEY smile? The absolutley crazy one?"
"It makes me laugh everytime i think of it. LOOTI!"
Ron: He's a Lootis man, look at his skullet.