Christmas

Christmas  is a holiday celebrated by some humans on December 25th, commemorating the birth of someone called "Christ".

It seems to revolve around the exchange of material goods, the slaughter and festooning of conifers, and the consumption of roasted avians. More importantly, it is the locus of a powerful "spirit" manifesting in charity, goodwill, and appreciation. Even hardened Decepticon warriors and vengeance-driven humans are subject to its influence.

Some Autobots have been known to don a red outfit with a bushy, white beard as part of the Christmas ritual. While not the most extreme example of quasi-fetishistic anthropomorphization among Transformers, this case is notable in its lack of explanation. Perhaps it is related to the similarly-opaque "Christ" figure at the center of the holiday.

Another human custom, Black Friday, is rumored to be the busiest day of shopping for the material goods needed for exchange on Christmas.

"Christmas: Date -- December 25th. Annual festival celebrating Christ's birth. Features include family reunion, gift-giving..."

- Starscream's "Internal Data File," Stargazing

Marvel Generation One comics
God bless us, every one.
 * The magic of Christmas made Circuit Breaker not kill Jazz.
 * The magic of Christmas made Jetfire appreciate his Earth heritage.
 * The magic of Christmas made Starscream realize that even if he doesn't care, helping people can make him feel... well, he still doesn't really care.
 * The magic of Christmas made Grimlock wear the Santa costume. So cute!
 * The magic of Christmas made Optimus Prime renew his pledge to protect Earth.
 * The magic of  free wine  Christmas made Darkwing & Dreadwind switch sides!
 * Optimus Prime shared a little of his own Christmas magic, healing environmental damage with a chunk of the Matrix.

Dreamwave Armada comics

 * The magic of Christmas made Iceberg be fascinated with it.

Transformers Animated cartoon

 * Powell was selling Familiar looking toys using Sumdac's technology. Sumdac considers it theft. Each toy has a mind of their own. One of them shocked the oil Sari Sumdac was making, causing the Autobots to sleep. The next morning, they were human.