I'mma give him a note 7

This is a Joe Biden meme. The joke in this meme requires the reader to know that Note 7s are known for exploding when used. If the reader knows that, then the joke is that Joe Biden is trying to kill or hurt Trump. Given Biden's public persona, it is hard to imagine him trying to physically attack Trump. The surprise that the reader gets when they realize that that is Biden's goal is the reason why this is funny.