Thermometer or Pen

A doctor is going about his business, with a rectal（直肠的） thermometer tucked（使折叠，收拢） behind his ear. He goes into a staff meeting to discuss the days activities, when a co-worker asks why he has a thermometer behind his ear. In a wild motion he grabs for the thermometer, looks at it and exclaims, "Damn, some asshole has my pen!"