Even an act as simple as building a peanut butter and jelly sandwich takes on an added level of complexity when you've got to do it in space. To show how zero G can effect even the most basic day-to-day details, Shane Kimbrough the Expedition 50 commander aboard the International Space Station shows how one gets made.
Even after reducing two slices of bread down to an easier-to-handle tortillia, Kimbrough has to keep everything in place with velcro to keep it from floating away otherwise. It's a balancing act that John Glenn first encountered with wonder after his first trip into space. In a pilot's report in 1962, he detailed how surprised he was with his own brain coming to logically understand the floating nature of space.
Kimbrough and his team aren't up there just to eat sandwiches, of course—they're looking at how "lighting can change the overall health and well-being" of those living in space, a growing concern with the space tourism industry on the rise. They're also looking at the properties of space-grown plants, which at least raises the possibility of someday not needing to bring a bottle of peanut butter from Earth to make a sandwich while floating.