Company 2D-Glasses make glasses that strip the 3D from 3D movies. Many viewers complain about eye strain, headaches and nausea when watching 3D movies, and this is one way to sit with your family and watch these movies. (The other options being 'close one eye for two hours' or 'don't go.')
Where to get them:
You have two options: Make DIY 2D glasses (You have to keep 2 unrecycled pairs of theater 3D glasses, then perform a lot of cutting and gluing.) Or you can spend $10 and just buy them. Your call.