Ice Poseidon is a former Runescape streamer on Twitch (now YouTube), known for his Jace-tier gamer humor, propensity towards getting fucked with, and his unusual reactions to things. He's shown up in so many "Song Request Trolling" compilations that nowadays people make entire ones just for him;
This is not the only thing Ice does on his streams though. One of the things that make him so famous is his habit of streaming out in public. Here he is being annoying at a McDonalds for an hour.
This behavior only increased with the launch of Twitch IRL. Here's some more videos;
He made international news after livestreaming on a plane like an idiot and getting swatted. As Kotaku mentioned he was actually permabanned on Twitch for this.
Most recently he's been involved in a situation with alt-right YouTube personality, noted drama whore and former BuzzFeed employee Baked Alaska, a summary of which can be found in his thread here;
Of note is that Ice is accused of dealing drugs to people like Baked Alaska and Andy Warski, and he is possibly getting arrested for handcuffing some pshyco thottie and staling her iPad.
His subreddit (a good place to start if you're looking for ridiculous moments from the dude): https://www.reddit.com/r/ice_poseidon