The English word van was borrowed into Welsh as
                              fan. This wouldn't normally cause too much of a problem;
                              man is most commonly treated as a masculine noun, and so
                              wouldn't undergo soft mutation to become fan.
                              However, like many Welsh nouns, man has traditionally
                              been treated as either masculine or feminine in different areas of the
                              country. The feminine form survives particularly often in idioms like
                              yn y man / yn y fan
                              (in a while). As a result, yn y fan
                              could mean in a while or in the
                                 van! Context will help you to decide which meaning is correct.