I am obviously not man enough to stay out of this fray, apologies all.

You have your EDC and your BOB is in the car. This should suffice in all but the most trying of circumstances.

However, as God apparently loves fools, as inferred from his / her / it having made so many of them, trying circumstances do occur. Forget the sensibility of the Rule of Threes or carefully thought out categories of survival gear, this is a fight or flight situation governed by the hind-brain we share with animals of supposedly lesser intellect.

Flight.

Often impossible without unwelcome social sanction, especially from one's significant other and family.

However you may scamper if you can get everyone else, including the wedding party, both of their families, and whoever is officiating, too drunk to care ....

Simulated acts of God with sufficiently major sound and visual effects can work as distractions - but only once: too much pesky explaining to do and no hope of trying it at a second event.

In any event you must loudly complain after-the-fact that you are not in any of the pictures!

Fight.

I hate to give up "A" material [or to have it traced back to me], so you did not hear it from me.

Lurid pictures of one of the couple-to-be-joined discretely left several places where they are sure to be found by their parents, the person designated to tie the official knot, and, most importantly, the biggest gossip in the place, can prompt a significant re-schedule. Photoshopping in a prominent guest may be required for effectiveness.

[Don't be stupid and just use a photo of the innocent about-to-be-newlyweds practicing for the honeymoon or work in the sex trade. That just shows you are unclear on several concepts, perhaps including a major reason for the timing of the nuptuals. It could just stiffen the resolve of many to use the sweep-it-under-the-ruglike hoped-for-sanctity, etcetera.]

Render the location uninhabitable, preferably in a temporary sense. Use natural, self-destructing timers or remote triggers, of course. [Consult with Blast or other suitabler expert as needed by PM; deal with witnesses in your customary manner. If you have not previously been this desperate, or not been trained by government service in this realm, then reconsider the flight options].

Direct confrontation and challenge to an immediate, honorable physical resolution of some fictitious but at least barely plausible insult, can work in the odd case. But you may find it is you who are considered the odd case and in a one-sided scrum with those highly motivated for the event to continue, or the authorities, or both. At least this will usually get you out of having to further witness that which you have chosen to oppose. I must caution this tactic has many potentially unfortunate consequences for your reputation, livelihood, etcetra. On second thought, get your sibling drunk and set them up for this.

Wardrobe malfunction has recently received a great deal of publicity and is a classic. In this let your imagination be your guide, but for heaven's sake, direct your attention to the bride's outfit as almost no one evens cares about the state of groom's attire. The more subtle approach would be to somehow contrive the complete absence of the wedding dress. Be advised that if detected and linked to you, either tactic may be seen as felonies punishable by immediate assault with fingernails and dress shoe heels by concerned female attendees.

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On the other hand, if you should for some reason find yourself in favor of the union, then first, beware all the above. You undoubtedly know who the usual suspects are, but if too dense to know, you are a guy and need to ask yor significant other.

Be sure to invite at least some EMT's, serving law enforcement, and, if all possible, your mom. In combination, they have everything needful close at hand and can get anything back on track.