My friend sent me this cartoon, among others, by email. The cartoonist depicts a scene between one worker and his fellow. One worker is disturbed because the vibrations of the other worker's leg is traveling through the ground and forcing his desk to vibrate. The forced vibration matches the natural frequency of his desk (or the frequency at which the object wants to vibrate) and thus the desk vibrates even harder. This is called resonance. That the shaking of one of the worker's leg could travel through the ground and cause the other's desk vibrate is a little far-fetched in my opinion. The joke of the cartoon is that instead of asking for the his co-worker to stop shaking his leg, the worker suggests instead that his co-worker change the frequency at which he shakes his leg so to match the natural frequency of the desk of yet another co-worker. If such is the case, resonance would occurs and if a drink were on the forcefully vibrating desk it would spill and thus the worker would have succeeded in frustrating his rival apparent.