On my first cruise that I ever took, there were 14 of us. Since we all had different tastes, we decided to book one excursion together on our 10 day cruise. We booked online prior to departure weeks in advance.
That day we were told that 2 of our party had to stay behind because they didn't have enough to fill a jeep. Apparently, you needed 4 per jeep and the way it worked out, not enough joined up. A couple stayed behind but the damage had been done.
Celebrity, being very appologetic to our needs, bought each couple a bottle of champagne and had it delivered to our staterooms with letters of apology for the inconvenience that had been caused.