A few years back when I was a medical student and calling in sick usually meant failing a rotation, I got a bad case of bronchitis while on the ENT surgery service and ran a fever of 102 F. Naturally, you have to be unresponsive and on a ventilator to get off sick (and even then you may have to make up the work), so I went in anyway after coughing up half a lung's worth of brownish-red phlegm in the sink (and since I was ill and fogged on cough medicine, I forgot to wash it down). That afternoon, I returned to find a trail of ants leading up to the loogie in the sink, and a ring of dead ants around it who had tried to eat the ball of sputum, failed, and died.