Then you get a photo of this:
Find a good one; one that matches his hair color du jour in the pic as closely as possible.
Then cut out that image, print it out on peel-and-stick paper, and get to work.
When I was a youthful junior officer, some wag--no idea who--did this very thing to a photo of our assholish commanding officer. They didn't use peel-and-stick, though; they actually took the pic out of the frame and inserted a perfectly formed horse's ass, going into the collar and everything, where the face should have been. The blend was close to perfection, because the colors were right. He was a pale guy and it was a pale horse.
We ALL saw it, and we ALL pretended we didn't see it. It stayed up for WEEKS. Since the guy really was a horse's ass, it gave me a great and quiet pleasure--I was saddened when the asshole (and yes, it was HIM who discovered it--even the XO somehow "missed" it) removed it. After that, he required the watch to check his picture daily and annotate that it hadn't been disturbed.
A real Queeg, that guy. But I still remember that Horse's Ass mashup fondly.