This is "Slumhog Millionaire", the mascot for the St Paul Saints (minor leage baseball). This guy was one ornery little rascal - shaking like crazy and grunting. They should use it as some sort of guard animal at night.
Random fact: Bill Murray is part owner of this franchise. Which is probably no surprise, as the games here are 100% entertainment (the baseball is good, but the antics are so unusual and outrageous).