Tinfoil Sail Hat

The latest design in tinfoil hats is a formfitting lightweight skullcap that incorporates a retractable sail similar to those sported by sailback dinosaurs, and for much the same purpose: both cooling and heating.

A series of quills form a line which runs from front to back, each connected to the next by a film of thermoconductive material (ie: tinfoil). An artificial muscle (powered by a coin-sized battery and activated by a sensor responding to an ear-twitch) erects the quills which lock into place, spreading the fins to form a "mohawk" sail from brow to nape of the neck. When facing into the wind it provides cooling for an overheated brain; conversely, when broadside to the sun most forms of mental blocks can be melted with surprising ease. Another flick of the ears and the quills drop back down, flush to the head.

The wearer isn't limited to ear-twitches either: the sensor can be adjusted to respond to eyebrow(s) raising, nostril-dilation and of course ambient or head temperature.