In the corporate workplace (aka 'circus'), refers to any individual, usually in upper-level management, that seemingly has little to no idea about what's going on.
"I've got a conference call with Norwood in ten - man, he's such a clown."
Acronym. Stands for "If you know what I mean". Mainly used in instant messaging conversations. Can also be used in conjunction with "AITYD" (and I think you do).