'I immediately need to talk about the 10 unhinged things that definitely happened on your Topdeck tour.'

We're right up the back of a crowded coach, hurtling down a road fit for a car advertisement in Lauterbrunnen, Switzerland when the tour operator's voice booms over her little headset microphone. 

Like a deeply-bogan Kylie Minogue, she stretched one hand above her head, bellowing above the din: "Orrrkaayy, guys! Time to come up with a tour song! Woooo!"

It's 2003, and I'm halfway through a 21-day Topdeck tour through Western Europe, the tried-and-tested route of a million Aussie gap-year backpackers before me. 

My best friend from home is beside me in the seat, and, having discovered approximately 17 minutes into this tour that we are not, in fact, 'tour people', her whispered response is grim. 

"What about … We gotta get out of this place?"

Watch: Group of friends start joint bank account for holidays. Post continues below.

At the time, the forced tick-a-box tourism and abundance of Southern Cross tattoos seemed like our worst nightmare — two small-town private schoolgirls who believed themselves somehow above the rabble.

We thought we were travellers, not simply tourists, with the ignorant arrogance of people whose life experience was mostly just listening to Jeff Buckley albums on repeat.

And yet, upon hearing the news that Topdeck tours is undergoing a 'brand refresh' — reducing group sizes (and the age limit) to appeal to a modern Gen Z traveller — I was overcome with nostalgia for the rite of passage that booze-filled, sex-filled Europe tours became for my generation. 

In no particular order, I present to you a list of iconic experiences that you most definitely had if you partook of one (or its more famous cousin, the Contiki tour).

Nocturnal bed-swapping and loud (bad) sex from the next bunk.

If you escaped a Topdeck tour without your ears being assaulted by the sounds of Trent from Newcastle finally being seduced by Amanda from Wagga after a night on the Absinthe in Prague, then you were probably… Trent or Amanda.

Whether you were on the hostel version of the tour (boujee) or the budget campsite option, privacy was non-existent and matches were made and unmade quicker than an episode of Love Island. 

The realisation that every group is just high school revisited.

On every Topdeck tour — filled with a mix of gap-year school-leavers and slightly older Peter Pan types — the social hierarchy would quickly be established. And no matter how hard you tried to leave behind the schoolyard politics, an Aussie version of prom king and queen would quickly materialise. 

The tour romance that the entire coach was invested in.

Speaking of prom king and queen, the alpha male and female of the trip would usually (but not always) be destined to share at least one night together. On my tour, Briony from Melbourne had a fervent on-off love affair with Sam from Sydney, and the ennui of their Romeo and Juliet story, destined for failure once they went home to their respective cities, clung to their every interaction.

He gave her his 'Europe Choons' mix-CD when the tour was over through tearful goodbyes.

Not socialising with a single person who wasn't from either Australia, the UK or New Zealand, in spite of being on a tour of Europe.

On a Topdeck tour, even a Brit was considered a rare, exotic creature. You'd generally engage with them in an Irish pub. In Germany.

Bek Day pictured on Topdeck tour bus. Image: Supplied.

Buying a Swiss Army knife in Switzerland, only to have it confiscated at customs before coming home.

Who can remember to move things to carry-on when you're hungover?

Throwing up on the bus.

Forget a 'tour song,' the true soundtrack to a coach ride around Europe was the gurgles of hungover twenty-somethings who consumed a litre of duty-free vodka in the previous 24 hours.

Wet T-shirt competitions.

File it under thing that we were completely okay with in the noughties that we'd now find problematic, but when one of my best friends on a separate tour sent word (via MSN messenger, of course) that she'd won a wet T-shirt competition, for which the prize was free drinks for the entire night, my overwhelming pride was just as strong as if she'd won an Olympic gold medal.

The shoestring budget.

Like the eponymous and dog-eared Lonely Planet guide every one of us had stashed in our backpack, everyone on a Topdeck tour is generally on a shoestring budget.

At the time, living on a diet of noodles and baguettes in order to afford vodka and Redbulls that night seemed like a necessary deprivation, but now, as I stare down the barrel of a five-figure grown-up Euro trip with my family of five, I long for the simplicity and romance of those days.

The random old guy who'd done a million of the exact same tour.

While the general demographic of these types of group tours has generally been the under-30 set, there was always one guy who loved his first tour so much he just kept coming back for more.

On our tour, his name was Thumper. 

The unparalleled freedom of realising the whole world was at your feet.

Sure, they might not have been the most authentic experience of European travel. We saw more of the inside of bars and buses than we did of actual culture, but for so many of us, it was the first taste of life outside our bubble — and it was as intoxicating as the lemon Stolis we mainlined the entire time.

Feature Image: Supplied/Topdeck.