It is a fun, free activity that may be mildly embarassing if you don't like being the center of attention for a few minutes.
To book this, make a PS for the Garden Grill. Ask the CM making the PS to note "rehitching ceremony" on your PS. 99% of the time the CM will have NO CLUE what you are talking about. That's ok -- just politely ask them to make this note on your PS because you know what you want.
Now, when you check-in with the CM at the restaurant, remind them that you want to do the rehitching ceremony. They should write this on your server's card as a reminder.
TIP: If you want to surprise your spouse, don't tell them and check-in at the restaurant while sending them away from the check-in station. It's even better as a "surprise!"
The ceremony itself is fairly simple: your server acts as the "justice of the peace" announcing that he/she wasn't invited to your wedding so now you have to re-do your vows! If your server does it well, they will announce this loud enough for clearly 1/2 the restaurant to hear!
You will be asked to exchange "I do's" again and then the fun part: you get to KISS while everyone counts to 100!
(They count to 10 by 1's, then from 10 to 100 by 10's.)
SOMETIMES, if the characters are available, they may attend the ceremony. Usually you will receive a certificate of the event. Sometimes at meals they will bring a cake for dessert (free).
They do the ceremony at any meal and also at the Ice Cream Social (seatings for this are 3 and 3:15). However, they do not serve the cake at the Ice Cream Social.
TIP: Book an early or later PS to avoid peak meal times. This can make it somewhat more likely that the characters may be around and available for your ceremony.
HAVE FUN!!