Colin must have inherited my thin blood, for he loves to be warm. Every morning, he comes downstairs and immediately sits on the floor vent that shoots up warm air from the furnace. During the day, he'll often bring his toys and sit on the vent, waiting for the occasional blast of air to keep the house at the toasty 22 C (or 23 C) I keep the thermostat at. We have lost some Lego pieces to the vent over the year, but that is a sacrifice he is willing to make, because no amount of my cautionary warnings will persuade him to choose another spot.
It's also really funny to see Caleb when he happens to be going by a vent and the air kicks on. He gets very excited and calls to Colin to inform him in the giddy way of a three-year old that the vent is on and the air is warm.