I refer you to Brian Lawsons comment, and also to the Reader's Digest book of Who's famous in your family, reprint 1986, page 26, Heraldry and the genealogist: Most, if not all, families can trace a connection with an 'armiger' - someone who has been given the right to bear a coat-of-arms. But do not assume that the arms go with the surname; they go to the lineal heirs of the man awarded them, in strict accordance with the laws of arms.

If you seriously want a coat of arms, you should read further on the subjectn and maybe even pay for an investigation. On the other hand, I don't suppose there is any harm in laying claim to a crest and having it on the wall or in the genealogy file, provided you treat it tongue in cheek.