Informal Lunch meeting in a company, where one person (from any department) volunteers to talk about a specific topic. Topic is usually related to the technology, business or market that company is in. Attendence is encouraged, but not compulsory. If your boss is going to attend, then to suck up to him/her, you may also want to attend. The Brown Bag term came up because everyone walks in with their lunch in brown bags, as the comapny does not pay for that lunch. Sometimes, sucker employees volunteer to speak at brown bag to show off their knowledge.
Hey, today at the brown bag, Jim, from TSD department, is going to talk up about nano technology.