Let's say two miners are trying to mine for the next block. The first one finds a block, and broadcasts it. The second one, on the other side of the world, doesn't hear of it for a minute or two, and in the meantime, finds another block off the same parent. They broadcast, but it's too late; the network's already seen the first block, and soon enough it's got a good few blocks following it. The second miner found a block, but it didn't make it into the blockchain. That's whatcha call an "orphan".

And a particular miner's chances of getting into that situation? That's the "orphan rate".

Seems most people have some smartphone thing. Scan your check and it forks over the cash.

'course, you could always do it other ways. Casascius coins, a store credit balance that you refill from home... plenty of options.

Local Bitcoins, sport.

Then, if your tastes are wilder, you can go to an altcoin exchange.