Today I saw a nice empty dialog from Adobe Reader on Windows 7... and I could not refrain from posting it, in the section "funny user interfaces".

Beside the fact there is no text at all, notice that is seems this should be a question (see the icon) but there is only an OK button. By the way, this was displayed as I tried opening a PDF in Google Chrome, and pressing the button did nothing (I mean, never got to see that PDF).