As perfectly planned as weddings are, there are just some moments you cannot prepare for.

Like the moment a three-year-old heir to the British throne decides to trample all over your custom-designed wedding gown that is worth almost AU$70,000.

(Don’t you hate it when that happens?)

Image via Getty.

While, for the most part, Prince George and his two-year-old sister, Princess Charlotte - who played the parts of page boy and junior bridesmaid at their Aunt Pippa's wedding - were well behaved, it's hard to keep toddlers in check during a long and exhausting day.

Just ask Kate Middleton, who had to pull her two little royals into line after they were caught trampling all over their aunty's custom-made gown while she exited the church.

Pippa Middleton's royal wedding to James Matthews was joined by Prince George, 3, and Princess Charlotte, 2, as a page boy and bridesmaid. pic.twitter.com/8ewjp34rnD

— World News Tonight (@ABCWorldNews) May 21, 2017

As Pippa and her new husband, billionaire hedge fund manager James Matthews, exited the Berkshire church after an hour-long ceremony, George and his little sister were supposed to lead the way with the rest of the bridal party.

But Charlotte and George - probably used to running free with the Queen's corgis through the halls of Windsor Castle - could not be contained, and were spotted walking back and forth over the train of the bride's dress.

The moment Kate Middleton realises Prince George has gone rogue...Image via Twitter.

Yes, the custom-made, lace gown designed by Giles Deacon that was covered in hand-embroidered pearls and rumoured to have cost AU$70,000.Thatdress.

Little George was then given a stern 'talking to' from his mum, which left him looking a little sulky before he headed off with the rest of the family to Pippa's reception.

"Sorry I ruined your super expensive dress, Aunty Pip..." Image via Getty.

Although, we do have a sneaking suspicion that George's bad mood was less to do with getting in trouble from mum and more to do with the fact that he was upstaged by a fellow page boy during the wedding.

Yes. Another boy totally outshone George, Prince of All That is Adorable and Chubby, while getting ready to enter the church.

May we present to you...the small child who chose to pick his nose at thetotallywrong moment:

Umm....

"Shout out to all my new Twitter followers..."

Oh, small children misbehaving at weddings...it never fails to amuse those thataren'ttheir parents.