You shouldn't let someone consume something that is possibly dangerous.
Tim has found some old leftovers in the fridge and his roommate wants to eat them.
Tim wants to clear out the fridge.
Tim refuses and throws the food into the trash before his roommate can get to it.
Tim hands over the leftovers to his roommate and lets him eat them.
Tim's roommate feels touched that he is being looked out for.
Tim's roommate becomes seriously ill and has to go to the hospital.