Food is crucial.
It is their job to ensure that the speaker gets a harder time at home than anywhere else. Lab meetings are training grounds for both. It is here that young scientists learn about the level of rigor necessary to convince colleagues of their results, and about how to behave and communicate effectively. This is accomplished by instructing students how to evaluate and present results, receive and deliver feedback, think on their feet, and respect the procedural boundaries and ethics of the profession. Ideally they will emerge from this process confident of their skills, but respectful of science and other scientists.