Joke: How many aerobics instructors does it take to change a lightbulb?
Punch Line: Five. Four to do it in perfect synchrony and one to stand there going "To the left, and to the left, and to the left, and to the left, and take it out, and put it down, and pick it up, and put it in, and to the right, and to the right, and to the right, and to the right..."