Max is one of the two titular characters of the Sam & Max franchise.
Max is a 3-foot-tall, white-furred anthro "rabbity-thing". His appearance is generally cute and cuddly, but contrasted by his enormous, sharp-toothed grin, which remains plastered on his melon-like head at almost all times. He has big feet and long ears that almost constantly stay upright, except for the few moments in which he's genuinely sad, as well as a pair of glaring, beady eyes.
Base your performance on the one made by Robert Tinkler in the 90s animated series.
Watch this video for reference: Sam and Max out of context