The present invention comprehends a forklift attachment, generally comprising a pair of forks rotatably mounted to a fork plate using a pair of pivot pins with each pivot pin having a center axis normal to the fork plate. Upper bore pins and lower bore pins are adapted to travel within bores of the fork plate. As such, actuators connected to the upper bore pin rotate the forks about the center axis such that the forks can apply opposing lateral compression forces to a flexible dumpster. In a method for collecting waste, a disposer places the flexible dumpster near the waste disposal site whereby a truck-mounted forklift can be utilized to engage the forks with the side portions of the flexible dumpster for loading and disposal. Accordingly, large dumpsters do not have to dropped off at the waste disposal site and large trucks no longer have to be utilized.