Chuckling out loud: used in place of lol, for when you are ACTUALLY
laughing out loud.
It's original
definition is "Chuckling out loud", used as a brief acronym to denote ACTUAL laughter in chat conversations.
Since lol is overused to the point where nobody laughs out loud when they say it, col is used to denote actual out loud laughter.
See: lmao, lmfao, rofl, lawl, heh, haha, lolol, and 120 for similarities.
Note that this is NOT a filler
abbreviation you use when you have nothing else to say.