H&M's design department in Stockholm, Sweden has a long-standing tradition of eating homemade cake [1] on Fridays. The designers take turns baking at home and then bring the goodies to share at work.

Most offices have their own traditions to promote a sense of camaraderie among employees and give the workplace more of a family feel. These can range from scheduled traditions like H&M's cake day, or more sporadic ones like passed birthday cards for everyone to sign.

Source [2]