Zac was the canvas for an 18-hour project to help medical students at RMIT University in Australia understand human anatomy.
Because, you know, the only true way to understand male anatomy is to get your face all up in it.
So Zac had to sit in his underwear for 18 hours while these lucky medical students drew lines on him with markers.
And all kinds of science.
And THEN, after "landmarking all the important muscles," according to lecturer Claudia Diaz...
Zac became full-on "anatomical man." Scary, yes, but it's for science, remember?
You can check out a video and more pictures of the frightening (and anatomically-accurate) final product at The Age.
And if the final product is too scary, just remember that this is what's underneath.
