Its an Emote on Twitch.tv thats usually is supposed to symbolize hype or excitment

A portmanteau of carpe diem, a Latin phrase that means “Seize the Day!” and DM, which stands for Direct Messages. This word means seizing the day via DMs.

Let me give you the complete etymology of this compound slang word.

It is correct that the first part of this word, POG, refers to the abbreviation for "play of the game". {Source: Wikipedia}

And so hence, Pogchamps would technically (and was probably intended to) refer to someone who is so good at a game that they always get POG.

However, gradually, this term has cultivated a new meaning for members of the streaming website Twitch.tv.

Now, Pogchamps exists as a versatile Twitch emote used to convey something or someone that is awesome and cool.
The first part of this term, pog, is also commonly used as an adjective or interjection to convey feelings of shock, excitement, and delight.

There is also now a online Chess tournament called PogChamps.

An absolute legend

A great emote twitch removed because gootecks(the face of the emote) had some things to say on Twitter about the capital that twitch didn’t like. Mainly used to show excitement or when something is really awesome. Other variants include pog, or pog with a word in front of it ex.

Tomatopog

Housepog

Storepog

Best twitch emote to ever exist. Used a lot by huge twitch streamer TommyInnit.

pogchamp, literally the word of happiness