Patches Google Chrome for Mac OS X's resource file to replace the incognito icon with Pedobear.
Basically, turn this:
into this:
Quit Google Chrome. (⌘-Q)
Run:
./pedobear.py
It should automatically find the resource file, back it up, and patch it with pedobear.
Open Google Chrome and open a new incognito window. You should see pedobear!
If you want to restore the original image from the backup, run:
./pedobear.py --restore
I've only tested this with Chrome v36.0.1985.125 but it should probably work until Google changes the incognito image again. I imagine you'll have to re-patch it every time Chrome updates, as well. I tried doing this as a Chrome theme and extension but neither seemed to be flexible enough to actually replace the image.
Pedobear icon courtesy of Miniartx on deviantart.