defamation
\Def`a*ma"tion\, n. [OE. diffamacioun, F. diffamation. See Defame.] Act of injuring another's reputation by any slanderous communication, written or oral; the wrong of maliciously injuring the good name of another; slander; detraction; calumny; aspersion.
hmmmmmmmmmm, that's from dictionary.com, i don't think saying a joke comes under it?
then again, this is the kind of person who uses "summer" as a verb;
"I summer in Barbados regularly"
