After watching episode 6x16 - What They Died For, I noticed that during the scene in which Jack and Locke are laughing in Jack's office, Jack appears to make direct eye contact with the camera.
I uploaded a screencap and gif of the moment here.
Larger version here
The thread has now escalated into an epic collection of images, gifs and videos onto which people have photoshopped what is becoming known as 'Ultimate Jackface'.
For those new to thread here are some examples:
(Images have been resized in order to fit here, full sized images can be found in the thread.)