I want to set my friend Luna up with someone, but we mostly know the same people, so I said I'll ask you, since you're now my blind date go-to guy. Your girlfriend's got any more brothers (or sisters, Luna's not picky)? I assume you're still together, because if I go on a blind date with her brother after you've broken up that might be awkward.
[ADDED: PRIVATE TO LUNA
Sam and I are going to set you up on a date with Sam's brother! I don't know him, but I'm sure he's nice, Sam's very nice.