RUGBY royalty Brian O'Driscoll and Amy Huberman will be issued with a good-etiquette guide should they take up their invite for the wedding of William and Kate.
The country's highest-profile Twitter couple are among the hundreds of guests who are being advised not to tweet from the church as the Prince and Kate Middleton tie the knot.
Other nuggets of advice dished out for Bod and Amy from St James's Palace are not to hug the queen, and turn off mobile phones.
Royal advisers says the guest list is an eclectic mix of European royalty, military personnel, charity workers, diplomats and friends of Prince William and his fiancee Kate Middleton.
Some invitees will have been born into families that teach children to curtsey as soon as they can walk, but others may need a bit of help navigating the etiquette and protocol that such an important day demands.
Anyone who is invited to the royal wedding will be given detailed instructions on how and when to arrive at Westminster Abbey, where the wedding is being held.
The first rule: Don't be late
"The Queen should be the very last person to arrive at the church before the bride and her attendants," said wedding planner and etiquette adviser Sarah Hayward.
"At most weddings, guests are asked to arrive around 20 minutes before the ceremony but the royal wedding will obviously have several important guests and very high levels of security so give yourself plenty of time to get there."
Choose an outfit that blends in
Women should wear a dress -- not too short, not too skimpy and certainly not white.
Most British women will complete the look with a hat or a fascinator -- which is a small feathered or jewelled hairpiece attached to a clip or a comb.
"Never ever ever do anything to draw too much attention to yourself," says Hayward. "It's the day the bride shines."
Men are asked to wear either lounge suits -- business suits by another name -- or a morning suit, formal attire that includes a long jacket and a vest.
A top hat should be carried, not worn, inside the church.
Remember, you will be seen together
"Often you see a husband and wife who look like they are going to two different events," says William Hanson, an expert on protocol who gives lessons around the world on proper behaviour.
"One person will be in something that looks like pyjamas and the other is in black tie.
You don't need to be colour-coordinated but you should definitely think about how your outfits look together."
TURN OFF YOUR PHONE
Guests may be asked by security to leave their mobile phones outside the Abbey, but if they aren't, they need to make sure a ringing phone is not heard by millions during a service broadcast live around the world. "The ultimate faux pas would be to have your mobile phone go off in the Abbey, even if you had God Save The Queen as your ringtone," Hayward said.
Tweeting is bad manners
"It's a private occasion and it would certainly be an abuse of the invitation to take photos or tweet during the ceremony or any point in the day," said Hanson.
SIp, DOn'T GULP
After the morning ceremony at the Abbey, some 600 guests are invited to a reception at Buckingham Palace, where the food and drinks are sure to be amazing.
Hanson advises guests to accept the offerings politely -- but don't gobble, don't gulp -- and for goodness sakes don't get drunk.
"Sip your drink, don't gulp it and always be aware how much alcohol you can tolerate," said Hanson.
"Don't embarrass yourself (otherwise) for you can guarantee you will never be invited to this kind of wedding again."
Watch your body language and don't touch the Queen
Michelle Obama put a friendly hand on Queen Elizabeth II's back during a visit in 2009. The Queen didn't seem to mind -- she even put her own arm around Mrs Obama's waist -- but guests at the royal wedding should be more distant.
"Never touch the Queen. Never initiate conversation with her or any member of the royal family. They will do all that," said Hayward.
The royal family no longer insists that people curtsey or bow to the Queen, but most people still do. "Nothing too theatrical," said Hanson. "Men should just bow from the neck -- a nod really -- and women should do a slight dip with their right foot behind their left foot."
However, Ronan O'Gara's choice of hands in pockets may not go down well with Royal aides.
After the wedding ceremony, Miss Middleton will be a member of the royal family and should be treated in the same manner as her in-laws.