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. 12. A method as recited in claim 9 , further comprising: outputting the statistically improbable phrase for selection by a user; receiving a selection of the statistically improbable phrase by the user; and responsive to the receiving of the selection, associating the statistically improbable phrase with the user and with a payment instrument associated with the user, a location associated with the user, or a delivery method associated with the user.