S1 Sam and Dean are on a normal, everyday salt and burn in the middle of the night. Only problem? The ground they have to shovel through is solid clay, riddled with pebbles and rocks. Dean's stuck on patrol, trying to make sure the spirit doesn't jump them, and Sam just keeps digging and digging, for hours. When he finishes, and they get back to the motel, his hands are torn up, blistered, and bleeding.
Dean tapes them up carefully -- each finger, and all up and down his palms -- making fun of Sam all the while. He continues his mocking, until he realizes Sam really messed up his hands and can't do *anything*.
If you want to include that his open wounds get infected and he's feverish and his hands hurt and he can't type, hunt, or research for several weeks, that would not be unwelcome, to say the least.
(And yes, this is based on personal experience, only my hands are taped because I went climbing for three hours after not having been for years. Whoops.)