The deacon is best man for Rolly's wedding to Aunt Leola. He is also paying for the wedding. He says he's spent $300 on photos; $450 on music; $600 for flowers; and $1,400 to cover the cost of the food.
The wedding scene at the end of the episode was filmed on location, at a real church. As a result, sound and lighting are much different in this scene than in the rest of the episode.