What should I wear to the meeting? You should go in your birthday suit.
Lillian told her friend to wear her birthday suit to the meeting as a joke. She learned this from high school when another friend said it to her. She said that to go in a birthday suit means to go naked. She accepts this speech and does not know where it could have come from.
Although this is a simple phrase, it can be interpreted in many ways. First off, teenagers constantly joke about nudity, especially with the media encouraging sexual references. This folk speech could refer to ones birthday, when one is the center of attention. A person could wear her birthday suit for somebody else, which would be a satisfying present.
Folklore is commonly spread in many ways, whether it is a couple words or a long story. In this case, simple phrases with sexual connotations are very common and easy to spread. By having words that refer to a completely different idea, people can have inside jokes with whoever knows the folk speech. Thus, there is an inside group who is familiar with the phrase, making it folklore.