After helping Andy Robinson's men to finish fourth in the Magners League, centre Cairns became the 17th Scotland internationalist on Edinburgh's books when he made his Scotland bow against Argentina last month.
But the 22-year-old revealed he faced an even more daunting examination in the week preceding the tour to South America; his driving test in nearby Currie.
Cairns said: "My driving test was probably the most nerve-wracking experience of the two events.
"I think a lot of people say that taking your driving test is one of the most stressful things they have ever done.
"I never really got nervous for the rugby match. To play for Scotland was a massive achievement for me and the fact I played the full 80 minutes in both Tests suggests I was perhaps doing something right."
Cairns has been duly rewarded with a new contract that will keep him in the Scottish capital until 2010; a fact that he is delighted about.
He added: "It's great to have signed the new deal. Edinburgh is my home city and I've lived here for pretty much my whole life.
"Last season was a great experience and the future is looking really good with so many young guys coming through. It is great to be able to play week in, week out with my mates."
Looking back at his first taste of international rugby, Cairns learnt a huge amount and believes he handled the challenge.
He said: "During the first Test I was just focused on making sure I didn't make any errors and to not look out of my depth. I was pretty happy with how it all went, although I was disappointed with the result.
"Then I knew I had to go forward from there and the second Test was awesome. We started really well and took the game to them; I got a lot more ball and made a few breaks which helped my confidence. "
The former Royal High student revealed he was looking forward to the next big match to be staged at Edinburgh's home ground, Murrayfield Stadium; when his favourite football team, Hibernian face Barcelona on Thursday (24 July, kick off 7.45pm).
He said: "I've got tickets for the game and I'll be going along with a few mates. My Dad grew up literally across the road from Easter Road and my Gran still lives there.
"We used to go around there and on match days we could actually watch the matches from her window. But now they've put the bigger stands up we can't do that anymore.
"I've not managed to watch Hibs play recently because of Edinburgh commitments, so it will be nice to see them play."
After experiencing such a breakthrough campaign last year, Cairns acknowledges he will have to work even harder to maintain his performance levels in the coming season.
He said: "I'm looking to carry on the form I managed last season into the new campaign. There is so much competition for places in the team and that has increased with Mossy (Chris Paterson) coming on board as well, so I will need to play well to keep my place.
"My first objective is to play well for Edinburgh and then after that I'll be looking towards making an impact for Scotland during the Autumn Tests and 6 Nations."
Head coach Robinson welcomed the news, but believes Cairns can still make improvements to his game.
Robinson said: "Ben has a good season last year culminating in his Test debut for Scotland.
"But it is important he continues to make improvements and that is why he has been given a two-year deal."
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