Just send a letter stating that there has been a mistake, because last time you went to have a pee, you noticed that you don't have a penis, so can't possibly be any type of man, free or otherwise...
Have fun with it, ridicule the sexist idiot for calling you a man...there's more than one way to destroy his credibility :D
Printed copy · Anthology Volume 2, page 161Printed copy from The Tender For Law Anthology, Volume 2, page 161 (printed 14 June 2014). Added by this site; not part of the Facebook export.