One is a rugby star, while the three others are all former Miss Ireland beauty queens - so what could they possibly have in common?
Still scratching your head? The answer is a shared fitness regime.
Leinster and Ireland rugby hero Rob has taken to attending the gruelling sessions at Beau Jacks Boxing Gym, favoured by the likes of Roz, Sarah and Lynn.
"You have come a long way @KearneyRob #lionsprep Now #rwcprep focus!" Beau Jacks shared on Twitter, accompanied with a picture of the 29-year-old looking elated after his workout.
The Dublin 2 boxing gym advocates a no messing approach to exercise - with trainer Steve Dawson regularly reducing people to tears or vomitting.
"“In Beau Jacks there are no ‘girl’s versions’ of exercises, there are no excuses and there are no breaks. The vibe is great and everybody encourages each other," top model and fitness fanatic Lynn recently said.
"It is an hour of pain, pure sweaty pain, but as weird as this may sound, I love it."
The Dublin model confessed she was not surprised that she vomitted after her first session of anaerobic strength training.
“It’s not the first time I have vomited while training and I am sure it won't be the last,” she shrugged.
Lynn was introduced to Dawson and the other trainers by her close friend Sarah Morrissey, and Tipperary native Roz Purcell is also regularly spotted in the ring.
The food blogger and fitness enthusiast agreed that it is unlike any other workout.
After her first time there, she joked that she will never make the mistake of wearing makeup to the gym again.
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