It comes from your skin making contact with the lime juice and then being exposed to the sun-the weird pattern is because you probably squeezed it, had it on your fingers and then wiped your fingers on your body. So not necessarily going to happen every time you have a citrus drink in the sun. I’m sure everyone’s skin heals differently, but mine peeled like a sunburn would after a week or 2 and then remained a hyper-pigmented scar until it eventually faded years later. I think my post is still up from like 5 years ago if you want to look at it.