When something is both tough and difficult. It implies that something is such a problem that it is both physically and mentally draining. However, it can be used in the humorous sense that something isn't tough or difficult but is tedious specifically for that person stating it.
Luke: "This year sucked man."
Adam: "Yeah man, having to move houses and being laid off. That's intense."
Luke: "Yup, it was pretty toughicult."