Most NFL champs rock their Super Bowl ring on their hand -- Green Bay Packers cornerback Sam Shields is wearing his on his NECK.

The 23-year-old defensive stud -- who was a rookie when the Packers won the Super Bowl this year -- rolled into the Ultimate Designz tattoo shop in Miami last week ... and pitched his ink idea to tattoo artist Sergio Garcia. He even brought in the ACTUAL ring for Sergio to study.

Sergio tells us it took about 3 hours to draw out the design of the tat (pictured above) -- and a little more than 2 hours to ink it onto Sam.

We're told Shields was a "really nice guy" throughout the whole process -- and even left a fat tip.