Also a "Cease and Desist" or other type of letter that a lawyer will send to someone, threatening a lawsuit. For example, when Slashdot users posted links to Microsoft's bastardized kerberos implementation, Microsoft's lawyers sent a nastygram to CmdrTaco and andover.net. A nastygram threatens litigation, but it is not a guarantee that any suit will be filed. They are used mostly as a scare tactic.