Taken from Zerohedge:
For those unfamiliar, spoofing is simple: it is the illegal practice of placing a large buy order just below other buy orders, or a large sell order just above other sell orders, then cancelling if it appears that the order is about to be hit or lifted. The idea is to make traders think that somebody with deep pockets is getting ready to buy or sell, in hopes of moving the market. If traders see a sell order of 2000 Bitcoin they may rush to panic sell before the whale crashes the price. And vice versa on the bid-side.
More at this link
