Father's Day
From Transformers Wiki
Father's Day is a human holiday, celebrating fatherhood and the bonds with their children. Cybertronians have taken part in it as well.
Fiction
Unite Warriors Offshot
After learning about human customs, the Technobots threw a party to honor their "father", Grimlock, while Sue Faireborn gifted her dad Dirk Manus a box of chocolate coins. Surprise Father's Day Party!!