AIM/iChat?

Anybody else been getting stupid messages from random people on AIM/iChat such as "Are you going to die?" or "Have you lied to your children today?" I got the former the other day, and the person said he got the latter from me; neither of us had actually sent it. Today I got the latter. It totally sounds like a virus or something, except that I thought there weren't really any Mac viruses out there.