'Bros and hos' etiquette.
I know the title is inflammatory, but it's concise.
Got invited to a birthday party by a friend (A). The party was at his friend's flat (B). A joint birthday.
Had an OK time. Chatted with an interesting woman, a friend of A. Couldn't find the right time to ask for the woman's number.
Later on, was chatting with B - he's nice enough, we'd met once before - and it turned out he'd asked for the interesting woman's number and had been given it.
Though the guy is friendly and we had a good chat, this didn't stop me emailing A and telling him to pass my details on to his female friend.
Your thoughts gentlemen? (And ladies.) If it was my friend who was interested in the woman, I doubt I'd have made overtures towards her. But since it was a friend of a friend, I didn't feel too bad. Apart from the fact he's was friendly to me and it was his joint birthday.
If it helps I think he likes to get as many numbers as possible, just to play the field.