I used that Bangor joke in my best man speech at my brother's wedding, but I phrased it thus:
"Anyway, I'll have to wrap up soon as Chris told me he's off to Wales in a minute" *look to groom* *receive puzzled look* "Didn't you just say to me "As soon as the speeches are finished, I'm going to Bangor?"" *bask in rapturous laughter and plaudits* *apologise to mothers and grandmothers in the audience* "To the Bride and Groom!"
When I did the speech for my best mate I told stories about the groom losing his virginity in a Mini, the number of sexual positions he's tried with his wife, and peeing down the stairs at his parent's house.