Pete Davidson is a captain at the Pro Bowl Games in Vegas this weekend -- which is sort of a weird sight ... but not nearly as bizarre as the ink Amon-Ra St. Brown was rocking.

The Lions WR was front and center Sunday for the off-weekend just before the Super Bowl next week, and during an interview with Robert Griffin III ... he showed off what appeared a relatively fresh tattoo he had plastered on his arm ... a tat of Pete's face, no less.

There's some writing underneath the drawing of PD's mug too ... it says, "Pete #1" -- as in Pete's #1 fan. Unclear if it's real or not, but Pete was brought over to take a closer look.