The Worst Man is a coveted position at all weddings ("Man" being a translation of the goblin person, of course, can be any species or gender) because it's so much fun. It's the Worst Man's job to break all the tension.
Groom is terrified he's going to lose something? Worst Man loses it first.
Bride has some nasty relatives she wants kept out of the wedding because they object to the other bride? Worst Man plays bouncer. Meaning they bounce the offending parties clear out of the county. Occasionally out of the time zone.
Caterer is fretting about the cake? Worst Man falls into it and wrecks it.
Father-in-Law is worried about Uncle getting drunk and saying something stupid? Worst Man gets drunker and draws all the attention.
Officiant gets stage fright and can't speak? Worst Man heckles them until they get angry enough to talk. (See "third wedding" above.)
Jealous friend saying rude things about the bride? Worst Man just dumps barrels of red wine on her until she shuts up and/or leaves.
After one's spouse, determining your Worst Man is pretty much the most important choice for a wedding.