Sheldon, Leonard, Howard, and Raj use negative reinforcement and positive punishment to keep themselves focused on their work. It doesn't exactly work as planned.
I like to use this clip and a couple of others to help firm up students' understanding of +/- reinforcement/punishment. After explaining the two axes of operant conditioning: behavior change (increase/decrease) and stimulus type (pleasant/unpleasant), we go through the clips and identify the behavior change and stimulus type. Then we decide if we agree with what the characters said was the form of operant conditioning.
Robin Roberson