I read this in an anthology perhaps twenty years ago.
There's a planet and the Earth people use the natives as a work force (maybe mining for some element) but a bit of trouble arises. A supervisor was idly chatting with his alien work gang and he mentioned Santa and Christmas presents. Now the aliens are stopping work because they want Christmas.
His boss tells him to sort it out, one way or another, or he's out of a job. Over several days he rigs up a kind of air sled and a costume and a load of cheap gifts, when he flies over the work camp the natives run around screaming "Sanny Caws! Sanny Caws!" in delight as he drops off the presents (they spoke a pidgin English)
The next day all are working as usual and he breathes a sigh of relief, until he realises they now expect Santa to arrive every year, unfortunately a year on this particular planet is only a few days long, therefore he needs to start all over again immediately