The Santa Cap, or Santa Hat, allows players to temporarily freeze the block they are standing on. The Santa Hat also gives players a higher top speed.
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Santa Hat

It can be earned in a random race, including campaign levels.

Blocks will not be frozen by the effect of this hat if they are touched from the bottom or the sides. The freezing effect will wear away in about two seconds, after which the block can be frozen again. One can notice an increase in speed as the wearer runs along the blocks.

List of Hats(Portal)
Kong Hat-EXP Cap-Propeller Hat-Santa Cap-Crown Hat-Cowboy Hat-Party Hat-Top Hat-Jump Start Hat-Moon Hat-Thief Hat-Jigg Hat-Artifact