Mattel - Long explanation, see below.
Toys R Us - Bain, along with others, bought TRU in 2005. Romney left Bain Capital in 2002, after 3 years of not being active in the firm.
Fingerhut - Bain bought Fingerhut in 2004. Romney left Bain Capital in 2002
KB Toys - Bain bought KB Toys in 2000. Romney left Bain Capital in 2002, after 3 years of not being active in the firm. KB Toys had been unprofitable for several years, and its parent, Consolidated Stores sold it to Bain.
eToys.com - Bain bought eToys.com in 2000, which bought the assets of the bankrupt eToys.com in 2001. Romney left Bain Capital in 2002, after 3 years of not being active in the firm.
laserhaas is alluding to Mattel's disastrous purchase of The Learning Company (TLC), which an activist site claims was part owned by Bain. The activist site also claims that TLC's books were cooked, but I've seen nothing to support either claim. I may be wrong, but it looks like Mattel was at the end of a chain of acquisitions: Softkey was a software company that didn't keep up with the market; Softkey bought lots of its competitors, eventually including TLC (which had also not kept up with the market); the newly merged company changed its name to The Learning Company; Mattel evidently saw TLC as an opening into the educational and kid games SW market, and didn't do its homework; lots of stupid stuff was done during the inflation of the DotBomb bubble, and this was probably the worst.
Almost all of the laserhaas claims I could track down were anachronistic wrt Romney - acquisitions made after Romney left Bain or during the 3 years Romney was not active in Bain. I'm guessing laserhaas was involved in a failing toy company Bain tried unsuccessfully to resuscitate, and laserhaas is blaming Romney/Bain for his failures that led to Bain acquiring ______. Obviously laserhaas made the transition from blaming others for his failure to obsessive hatred of Romney.