Yes and no...
The squirrel I found a picture of online, but the quality sucked, and it was too small to work with. So I drew it in pen, scanned it in, and colored it with photoshop. Text and effects were done with photoshop, and I found the machine gun online, cut it out of the original pic, sized it to fit, and pasted it over the squirrel. Then reworked the squirrel to make it look like he was holding it, and redid the outlines of the gun to match those of the squirrel.
This is one I did from scratch by hand last year:

And one from a few years ago.
No photoshop on either of those two.