There are several ways of getting a job testing toys. Large toy companies often sponsor community-centered events that allow people to test toys. At least for a short while you can get to test some cool new toys. Most of the toys you will be handling are still in the “drawing board” stage and are probably not for mainstream distribution just yet.
If you want toy testing as a regular job, you have two immediate avenues to explore: malls and factories. Malls have separate sections for toys; you would probably get a job as a demonstrator (and not really a tester, in the sense that your input will have a bearing on the final form of the toy).
Do you feel that somehow, toy testing would be a step down from what you usually do? Then try your stuff at video game testing. Basically, video games are still toys (albeit more expensive, sometimes). What you need to do is to browse the company websites of outfits like Blizzard North and Electronic Arts and inquire whether they are in need of video game testers.
If not, you can still wait for these companies to post announcements regarding beta-testing. Beta-testing is basically trying out a new video game before it is finally released to the market. You gain exclusive access to a video game before the rest of the gaming population does, but you have to report your over-all gaming experience plus game bugs or errors if you saw any.
If there was anyone occupation to satisfy the "Big Kid" in us all, it's becoming a toy tester. Just be prepared for the potential snickering that may come from those who are jealous.