I broke down and bought some knock off Birkenstock this weekend. I didn't really look twice at the label, but when I got home I realized they were Birkinstick. I had a good laugh about this blatant infringement. Apparently Birkenstick is even a registered trademark as per the circled R.
Let's see Birkenstock cost about $80-$100 USD. Birkinstick on the other hand cost $12 USD, bargain shopping!