Wrap the can in some insulating material. This could be a blanket, a towel, foam padding, bubble wrap, cotton stuffing, styrofoam, neoprene rubber, even newspaper. The better it is wrapped, the better insulated it will be. The more dead air space (in other words empty space inside the thing you're using to wrap the can) the better.
The best form of insulation is a vacuum, and that is how many thermoses are insulated. You can't use this unless you design a special can first however. Any of the items listed above can just be wrapped around any can (or anything else for that matter)
See the Web Links for more information about thermal insulation.