I bought some tofu at the store about a month ago (or was it two months?). Anyway, I haven't eaten it all and it's sitting in my fridge in tupperware. How long is it good for?
Throw it out.
Tofu has a very short life. Once opened it can last up to 5 days in the refrigerator, but only if you store it submerged in water, and change it daily.