The BSUSB (or a Bifurcating Systematic Universal Stop Button) is a invention developed by Live Corp Thinkquanauts supposedly to stop the FLDSMDFR once and for all. It's kept by Flint during his journey through the Food Animal Jungle on the Transformed Swallow Falls.
After finally reaching the FLDSMDFR Flint realizes that the machine and it's Foodimals are not dangerous. However Chester V plugs the BSUSB into and reveals that what it really does is reprogram the machine to it to a Live Corp setting. After freeing the FLDSMDFR from the Live Corp Factory, the BSUSB is removed and the machine goes right back to making more Foodimals.