Used in live chat to express laughter and; confusion, disbelief, or lack of understanding. Often used in a mocking fashion.

Often written in all-caps for effect. Question and/or exclamation marks are optional.

A term used to express simultaneous confusion due to a presumably inaccurate, misinterpreted, or absurd statement and laughter, nearly always due to this aforementioned PIMoAS.

something funny but you dunno what it is

Used to describe surprise and confusion when someone tells you something or you overhear something that is funny or out of the ordinary.