Just have one.
The bride and groom had just two requests. One, "Ain't No Sunshine When She's Gone," was a cakewalk with a tailwind. Easy-peasy. The Claymore, which, to protect the guilty, I won't name*) was the only song to ever earn a unison "Oh, no!" from the whole band.
First practice, we slogged through it, miserable, and made a complete hash of it. Then it hit us all at once: The only way to survive the ordeal was to really throw ourselves into it, like we meant every note and word. (I think it was Charlie Brown who said, "Always be sincere, whether you mean it or not.")
So we swallowed our gum, slapped on our grins, and for another three or four practices, plumbed the depths of our little hearts and souls for that insipid bit of pop fluff. At the wedding, we nailed it, even the dual vocals. Afterwards we celebrated never having to play it again.
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*Hint: Did you ever see a TV show called Friends?