I'm watching this, and I have thoughts I'm not saying out loud.

Excellent, impressive — a complete compliment with no words needed.

Overwhelmed — usually with laughter, sometimes with genuine emotion.

Laughter — and, to younger users, a signal that the sender is over about thirty.

I'm dead — meaning something is extremely funny, not morbid.

A sceptical or disapproving look, or the written equivalent of one.

Laughing extremely hard — or occasionally, genuinely moved.

Excellent, impressive, extremely good.