Followers of Conor McGregor were quick to point out the red marks on his right shoulder as the UFC star posed for a picture with Chris Brown.
The Notorious partied with American singer Brown ahead of his shows at the 3Arena in Dublin.
However, it was the red circles on the upper part of McGregor's arm that a number of people spotted.
One wrote: "What's the big red blotches on Conor??"
Another asked: "Conor what are the red marks on your arm?
Someone else said: "Why does Conor have pepperoni on his right shoulders."
The marks are the result of 'cupping'
Cupping is popular with celebrities and among those to have tried it are Kim Kardashian, Justin Bieber, Jennifer Aniston, Victoria Beckham and Calum Best.
It sees suction cups placed on a person's body to remove toxins.
It is said to aid physical recovery by easing pain and reducing inflammation in the body and it is understood that it particularly helps with joint and muscular pain, while speeding up the recovery of soft tissue.
The most decorated Olympian of all-time, Michael Phelps, is another fan of the therapy and has appeared at the Games with marks from it clearly visible on his body.
READ NEXT:
Amy Broadhurst and Lisa O'Rourke won't defend World crowns as IABA takes stand
'They all look up to him' - how James Ryan has become a leader for Ireland
Vera Pauw says it's a 'shame' Ireland won't get Aviva Stadium World Cup send off
Rory McIlroy mocks LIV rebels Patrick Reed and Phil Mickelson in Netflix series
James McClean plays for Wigan hours after birth of baby daughter as wife Erin hilariously reacts
Get the latest sports headlines straight to your inbox by signing up for free email alerts
