Halloween

Halloween is an Earth holiday in which humans dress up in strange outfits that make them look like other people or things.

"So, the purpose of this "Halloween" is to disguise yourself in order to frighten strangers and extort sugar infused...nuggets."

- Optimus Prime contemplates the true meaning of Halloween

Transformers Animated cartoon
On Halloween night, Bumblebee and Bulkhead went trick-or-treating with Sari. They were spotted by Blackarachnia who at first looked like a Halloween decoration which Sari used to pull a Halloween prank on Optimus, Sari put a big spider up in front of him which he chopped up with his axe. After Blackarachnia took the key she used it to turn every organic into older, wrinkly versions of themselves. Eww.