I wondered if he would like a monster face there, something I had seen on Pinterest. He was charmed, and I amused myself one Sunday afternoon with needle, thread, and fabric scraps.
I did the patch entirely by hand so I didn't have to rip open the side seams to get the leg into my sewing machine. It was not as difficult to hand-sew through denim as I thought. We love Ben's monster, and he often gets compliments when he wears the jeans; in fact, he styled himself on Sunday with a sweater vest, red bow tie, (orange snow boots - whoops, forgot the penny loafers at home), and his monster-knee jeans.
The robot came about because I bought Ben a plain green sweatshirt at the thrift store and offered to embellish it for him. He drew a robot for me, which I had to modify to sew, which did not please him, so we had to go back and forth several times at the drawing board.