1. The bike looked great online, but it was far too heavy, and the steering was rubbish—I bought a real pig in the poke.
2. Some people think that buying stuff on-line is like buying a pig in a poke.

A poke is a sack or bag, from French poque, which is also the etymon of "pocket", "pouch", and "poach". Poke is still in regional use. Pigs were formerly brought to market for sale in a cloth bag, a poke.