The average wedding costs a hefty sum (£24,000 in 2016, according to MoneySavingExpert). So imagine the sheer rage when an old mate from university drinks the bar dry, makes a pass at your newly-minted mother-in-law and then proceeds to give the toilets The Exorcist treatment (causing yet another eye-watering fee).

The lesson? Don’t be that guy. Or any of the guys mentioned here. Be more like Myles Usher, the etiquette expert behind speech coaching service Speak-Well, who has a few tips for navigating nuptials without being a douche bag.

Downwards Trend

Wedding photos last forever, trends less so. Therefore it makes sense to keep your attire classic or risk eternal shame on the bridegroom’s mantelpiece.

“Don’t bend to a fad,” says Usher. “Always lean towards tradition, as a well-tailored suit will never let you down nor age with the seasons.”

Master Of Ceremonies

A mate’s wedding makes for prime time viewing, but a Superbowl party this is not. So behave accordingly.

“Being hammered or hyperactive during the actual wedding service is a definite no-no, so don’t turn ‘Lord Of The Dance’ into a football chant,” says Usher. “Remember, it’s an honour that you’ve even been invited, so treat your role with the respect, duty and decorum it deserves.”

Evacuate The Dancefloor

Throwing wild shapes may lend themselves to a 4am rave, but they’re wildly inappropriate at a wedding. Swerve a dance floor emergency with some restrained choreography.

“Unless classically trained or a direct descendant of Fred Astaire, don’t hog the dance floor with your tie wrapped around your head,” says Usher. “It’s there for everyone to enjoy, so keep it smart, simple and respectable.”

Time Lord

On the big day, the happy couple will be more a peeved pair if you rock up half an hour late. Save the excuses and set your alarm early.

“Punctuality is the politeness of princes,” says Usher. “Ceremonies and receptions are often subject to the strictest of schedules, so the least you can do is be on time.”

Maiden Voyage

Despite the old cliché, the maid of honour isn’t reserved for the best man. Which means she’s off-limits to you, too.

“In the same vein of not sleeping with one’s work colleagues, keep relations at the wedding wholesome,” says Usher. “Dipping your pen in the office ink can lead to all sorts of embarrassing social situations in the aftermath.”

Sober Up

The only thing worse than a dry wedding is a guest that exploits an open bar. Go steady on the booze or prepare to be the talk of the top table and beyond.

“Remember that you are sharing in the joy of the happy couples’ day – and the key word here is sharing,” says Usher. “Don’t upstage the bride and groom by whooping like a TV audience member during the speeches. Just take it easy on the drink front, lest you be the guest that everyone remembers for the wrong reasons.”

Meeting Minutes

Face time with the bride and groom may seem important, but remember they’ve got to do the rounds with every guest – even that weird estranged cousin on the back table.

“Don’t be an irritant and demand a lengthy audience with the stars of the show,” says Usher. “You will appear desperate and pathetic to fellow guests, and they’ve got at least a hundred other people to give their thanks to.”

Keep It Schtum

A stellar speech is an art form in itself, and they often take months of practice to get right. Don’t steal anyone’s thunder by tapping your glass when not invited to do so.

“An unsolicited speech will upstage the preparation official members of the wedding have put into theirs,” says Usher. “Plus, chances are it’ll be damned awful, so keep the emotional declaration to the wedding card or the guestbook.”