Oh my. Those are "stretch marks." Guys typically get those from exercising arm muscles. I guess females could get those too, but stretch marks only appear on skin after some kind of rapid bulking up of the body in the area. Rapid [fat] weight gain, and rapid muscle building stretch skin and leave those marks. Those marks, at that particular location on the arm is a sign of rapid arm muscle build up typically seen on males who exercise.

For clarification, females sometimes get those stretch marks on breasts, if their boobs bulk rapidly. But the arm bicep stretch marks are far more commonly seen on males.

I'll be honest, I always considered the "Big Mike" thing a humorous meme. But seeing arm muscle stretch marks- provided the pic is real, gives me pause. That's a guy thing.