Joseph wanted to be remembered by those that he interpreted dreams for. He could have lied to Pharaoh's baker in hopes that they would have mentioned him to the pharaoh quickly, or to spare the baker's feelings. But in the end we see that it was his integrity, his desire to be truthful and the events playing out as he said they would that broke him out of his prison. 

Don't lie to protect people’s feelings.

Doing what's right is always better than doing whatever it takes.

Faith allows for integrity in the face of trials.