Grimes’ tattoo is a bold move — one ya gotta make to shock people with tattoos these days … so says a celebrity tat artist who has been around the block a time or two.

We caught up with Mark Mahoney — a pro who’s been practicing his craft for nearly five decades — and we showed him Grimes’ new controversial tattoo … which is basically a big red circle that looks almost like a scar around her eye.

Mark — who has tattooed stars like David Beckham, Lady Gaga and more — says even a small tattoo on the arm used to shock old ladies at the store … but, in today’s culture, shock from tattoo is reserved for the wild and crazier ideas — which he thinks might be the reason Grimes decided on this design.

Mahoney says part of the fun of tattoo is to shock people … and, he’s all for Grimes’ “cybersigilism” tattoo — an emerging style that blends ancient symbolism with digital aesthetics.

We asked Mahoney if he tries to talk his clients out of crazy tattoos like this or if he’s always down with the wild ideas … and, Mark says he’s in the latter camp — he’s even done a face tattoo before. Watch the clip all the way through to hear that wild story.

Mark was one of many big stars at Posse’s Spooky Soiree earlier this week … with Chase Hudson leading the bold-faced names in attendance.