LoL, Scrubbing Bubbles. A couple years back, they had printable coupons for $3 off... so when they went on sale, you could get them free. Some people bought them by the carton.
I probably got about a dozen boxes. I find them to be pretty useless though. I don't think it does anything to help keep the bowl cleaner... but my plumber friend says it prevents the water ring from building as quickly.