A class professor was giving a lecture on company slogans and was asking his students if they were familiar with them.

"Joe," he asked, "which company has the slogan, 'come fly the friendly skies'?"

Joe answered the correct airline.

"Brenda, can you tell me which company has the slogan, "Don't leave home without it?"

Brenda answered the correct credit card company with no difficulty.

"Now John, Tell me which company bears the slogan, 'Just do it'?"

And John answered, "Mom...."