As part of your speech, get as many of the women in the room to "return" keys to your buddy's place. old, young, in-between, and especially the bride's mother, the maid of honor. It works best if you call up the Mother-in-law to be (you better have cleared it with her in advance !!) As the last to return a key, get one of the guys to sheepishly bring up a key, or return your own key to his place.
Follow this with a rendition of how good a friend he has been, since you and the rest of his friends love him as your best friend, he loves her, then you all love her by extension and you welcome her to your circle of friends. At this point you might ask the guys in the room to return their keys to her place.
If the crowd, especially her family, does not have a sense of humor, then your f****d and I have no more suggestions for you.