Just finished drinking a couple of liters of sextuple-chocolate ice cream mudshake that I knocked up in the blender about half an hour ago.
Basically just tossed half a tub of light, and dark chocolate ice cream, with dark chocolate ripple sauce throughout it, some milk, white and milk chocolate curls into the blender, and whizzed it up with a 2-3 tablespoons of cocoa powder. 'Twas absolutely delicious, nice and icy cold.
Wouldn't mind trying the same using macdonald's milkshakes, either banana (if they still do it, not sure if they do, but the banana ones were always my favourite from there), or vanilla, as the base, just a little milk to thin it down, and more of the same ice cream+cocoa powder. I bet it would be lovely made with a rolo milkshake too.
Perhaps throw in a few shots per pint of russian standard, to make a vodka mudshake, give it a little bite.