You can still let friends fly on the ticket; just check in at the airport and then hand them the ticket. Assuming the party to whom you're giving the ticket is of the same sex they'll have NO problem on the return flight providing you give him/her a valid photo ID; the agents NEVER look at the pictures, they only marginally match the name up with the ticket. I emphasize that this is not illegal (at least on the outbound portion) but does violate all FF program rules so at worst you'd get bounced.

Or, if you're not sure you're going to be able to use a ticket just buy on-line with an expired credit card -- as a top tier flyer they invariably will force the fare later when I call the day prior to departure and play dumb "what happened to my electronic ticket?" Sleazy yes, but so are the airlines...