As enthusiast photographers, we don’t mind when friends take advantage of our good will and photographic know-how. We are glad to contribute to a happy day and take candid pictures of family and friends while the hired pro records the event for posterity.
You did hire a professional wedding photographer, right? No?
Unless you are asking your professional wedding photographer friend for a favor to take your wedding photos for free, you should not rely on an otherwise landscape/sports/macro/occasional wedding photographer friend like us to take on that role — unless you are willing to risk not having proper wedding photos.
Taking the planned shots versus taking the candid shots are two very different jobs and you should really entrust them to two different persons: the first to a professional wedding photographer and the second to, well, almost anyone else who has a camera and aim to impress.
By the way, the tongue-in-cheek poster and many other photography-related ones are available for purchase at the shoppe.