Since Christmas often means snow (at least for us living in the northern hemisphere) I thought to try to generate some snowflakes on the micro:bit.
Since snowflakes are symmetrical, we should only have to create a 3x3 corner and rotate that 45° at a time that to get the full shape.
End result might resemble a star-wars spaceship instead of snowflakes.
Equally seasonal?
Here's how it looked like:

and here's the code.