Leo Cullen does a pretty good poker face, particularly on the big weeks, but even he broke out into a roar of laughter at this afternoon's weekly press conference at UCD.
In a break from Leinster's normal schedule, the head coach was up at the top table for the first briefing of the week, but this was a one-off appearance as he sat in for the unveiling of the latest addition to his coaching ticket: double World Cup winner Jacques Nienaber.
The South African was speaking to the Irish media for the first time since landing in Dublin just over 10 days ago, ready to dive in at "the deep end", to use his words, into his latest project.
It's less than six weeks on from the Springboks' Rugby World Cup title success, a second in a row for the South Africans under the dream team of Nienaber and Rassie Erasmus.
The job titles may differ this time around, but the balance of power appears to be similar, so it was the suggestion that Cullen will be his "new Rassie" that tickled the Leinster boss, as he sat beside the new senior coach.
"We only know each other for a week and I know Rassie for 30 years so I think eventually we will get to that level," Nienaber smiled.
The 51-year-old's move to Leinster has been confirmed since last April, with Nienaber replacing Stuart Lancaster following his departure to Racing 92. It was a signing that caused shockwaves globally in rugby; very few club sides in the game would have the cache to draw a World Cup-winning coach out of Test rugby, particularly when it wouldn't be a head coach or director of rugby role.
But with Test rugby pulling Nienaber away from his family for such a long period of time, Leinster represents the "best of both worlds".
"International rugby is a little bit different in terms of the duration of time you're away," he explained.
"You only play 13 Test matches but for us - South Africa - I think I was away in this World Cup year for six months and one day from my family and my home.
"Although there's 28 games or more that you play for the club, you're more frequently at home. We're away this weekend [v La Rochelle], but I'm at home during the week, which is something international rugby doesn't give you. You're away and you're always away.
"I felt I needed a change from international rugby, so needed to get out of international rugby."
And while Nienaber is taking a step back from the Test scene, he says the pressure and expectation to win at Leinster means there will be no drop in standards.
"When this opportunity came up with Leinster, you get the best of both worlds. You get some more time with your family, but get the environment that will not tolerate mediocrity.
"As a coach, you can't drop your standards that you've delivered at the international level. The players you work with are international quality, so they'll make sure you're on your toes. You can't just spin a story, they'll see right through you.
"The coaching group is massively experienced and the playing group is massively experienced. From a personal point of view, it was a perfect fit. A little bit more family time, but from a work perspective a massive challenge.
"I think the pressure that will come with the job, the expectations of Leinster will be similar to what I faced with South Africa. It's just, I think the whole Leinster environment, I think there's a lot of people worldwide that support Leinster.
"I think it's got a big world following, and a lot of people look up to Leinster, even in South Africa, just purely because of the way they conduct themselves on the pitch. The type of rugby they play, a lot of people enjoy that, so there will be a lot of pressure from all over."
While Nienaber is still figuring out his way around Dublin - he says his first success has being finding a good spot for a coffee - he's no stranger to Ireland, having spent 18 months working with Erasmus at Munster in 2016 and 2017, bringing the province to a Pro12 final before the pair left abruptly to join the Springboks.
And the defence specialist says he's looking forward to returning to Thomond Park on St Stephen's Day, when Leinster face the URC champions in their annual Christmas Intepro.
"I think I'll get more flak from the Munster supporters than from the South African supporters. I mean, South Africa supporters, we were open and honest, the move was announced way before the World Cup, and it was for personal reasons back then. I really, honestly think I would lose my family if I kept the international rugby, I felt I needed a bit of a break.
"We'll probably find out when we go to Thomond Park in a couple of weeks. I don't think they'll buy me a pint," he laughs.
His main brief at Leinster will be around defence, which was his area of expertise at Munster and with the Springboks before stepping up to the head coach role.
And while his South African world champions were heralded for their fast and aggressive 'D' during the World Cup in France, Nienaber says he needs to cut his cloth to suit the measure, rather than a "copy and paste" job.
"I don't think you can copy and paste a system, any system, attack or defence, from one team to another.
"The thing that makes a system is the athleticism you have available in your squad and the skillset you have in your squad. Obviously the skillset and athleticism of South Africa versus what Leinster have is different, so you have a general, broad way of how you would like to do things, but you have to be able to adapt to the group you have.
"Where I am now, it's trying to find out what skillset and athleticism we have in the group and how we can utilise it in a system I've got in my head. I think if you just copy and paste you might end up putting certain players in a box where they have a certain skillset and they can't utilise that skillset in a game.
"Evolution comes sometimes with success and sometimes with failure. That's how you evolve, that's how you learn what the group will be able to do."
Follow a live blog of La Rochelle v Leinster (Sunday 3.15pm) in the Investec Champions Cup on www.rte.ie/sport and the RTÉ News app.
Watch Munster v Bayonne in the Champions Cup on Saturday from 4.45pm on RTÉ2 and RTÉ Player, follow a live blog on www.rte.ie/sport and the RTÉ News app or listen to commentary on RTÉ Radio 1.
