A positive review you give to a movie, book, TV series or CD that you don't like but which a friend has recommended to you, usually because you don't want to hurt their feelings.
Rod: I watched that movie The Departed last night which John lent me.
Tom: What did you think?
Rod: I hated it.
Tom: Oh boy, he loves that movie. What did you tell him?
Rod: I told him it was great.
Tom: You gave it a friendly review, huh?
Rod: Yeah, you know what he’s like.