9. A method implemented at least in part by a computing device, the method comprising: determining that a source includes a statistically improbable phrase; and based at least in part on determining that the source includes a statistically improbable phrase, storing the determined statistically improbable phrase in a corpus of phrases for use as an identifier, wherein the statistically improbable phrase, when received before or during a transaction, provides access to a payment instrument for use in a transaction.
9. A method implemented at least in part by a computing device, the method comprising: determining that a source includes a statistically improbable phrase; and based at least in part on determining that the source includes a statistically improbable phrase, storing the determined statistically improbable phrase in a corpus of phrases for use as an identifier, wherein the statistically improbable phrase, when received before or during a transaction, provides access to a payment instrument for use in a transaction. 10. A method as recited in claim 9 , further comprising outputting the statistically improbable phrase for selection by a user.