Delegation

In order to ensure we're on the same flight for an upcoming ski vacation, I offered to book reward travel for a friend. Sequence went something like

Me->Friend: I need your account & password to book reward travel.
Friend->Asst: Please give Paul the info.
Asst->Me: Here is the account number.
Me->Asst: I also need his password.
Asst->Me: Here is password (it is Friend's phone number)
Me->Asst: I should have guessed.
Asst->Me: It needed to be something I could remember.
.
Me->Site: I am Friend and this is how I prove it.
Site->Me: Looks OK, welcome Friend
Me->Site: I, Friend, want to book this flight on points.
Site->Me: Sure thing Friend, how do you want to pay the taxes?
Me (thinking): Don't have Friends credit card, I'll use my own and Friend can pay me back (hopefully).
Me->Site: Here is my credit card info.
Site->Me: Hey, nice try Friend, but that's not your card.
.
Me->Friend: Book it yourself Mr. "Big Shot, look at me, I have an Assistant"!