Have you met (followed by a name) is a recurring Catchphrase which has been featured in the show multiple times. The phrase is used by a person's wingman in order to introduce the person to an attractive woman (or man).
The wingman walks up to an attractive woman at a bar and starts a conversation with her, before suddenly asking the women "Have you met __?" which is when the wingman walks away and the women and the man start talking. In the series this catchphrase is mainly used by Barney whilst acting as Ted's Wingman at MacLaren's Pub.
The phrase dates back to the Pilot.