Tomfoolery (noun)

Foolish or silly behavior; foolishness.

Origin:

The word "tomfoolery" comes from the word "tomfool" meaning a simpleton or a fool. it has been used since the 17th century.

Examples:

1. The kids were engaged in tomfoolery when they were supposed to be studying.
2. His tomfoolery was not taken seriously by anyone.
3. The tomfoolery was causing a disturbance in the classroom.
4. He was always up to some kind of tomfoolery.
5. The tomfoolery was not appropriate at a formal event.