Things that are really hyped up but are then gigantic failures, so much so that its funny. E.g. The great leap forward, Star Wars: The Phantom Menace, The Rockies in the world series.
During the great leap forward the communes claimed to be producing surplus amounts of food when actually they were producing much less, resulting in a famine which killed enough people to compare to the holocaust. ROFL MAO!
To borrow something and never return it, intentionally or otherwise. Different from stealing in that the item will (initially, at least) have been given freely.