DETROIT — Calvin Johnson gives friends in the NFL and other players he admires the shirt off his back — literally.
The Detroit Lions superstar has exchanged jerseys with fellow receivers, Pittsburgh's Antonio Brown and Cincinnati's A.J. Green, this season and has a collection of keepsakes on hangers in his closet.
"I've got eight to 10 hanging up and eventually I'm going to get them signed and put up in my basement in frames on the wall," Johnson said in an interview with the Associated Press. "I can't tell you when I first started doing it."
He doesn't expect the next time to be today after Detroit (7-6) hosts the Baltimore Ravens (7-6) in a possibly pivotal matchup as both teams hope to close the month well enough to be in the playoffs.
"It's nothing personal, but I don't know any of those guys very well," Johnson said.
"I usually know before the game if it's going to happen. I knew I was going to trade jerseys with A.J. because we train together in the offseason. Sometimes, I'm just a fan of the guy and we'll switch jerseys."
It's a fitting ritual for the Lions' most humble star player since Hall of Fame running back Barry Sanders simply handed or tossed footballs to officials after scoring more than 100 times from 1989-98.
Johnson has more of an aw-shucks personality than a look-and-listen-to-me persona that many players have and have had at his position.
Brown said it was a "golden opportunity" to swap jerseys with Johnson last month. The Steelers standout has been looking up to Johnson since 2007 when he was a freshman at Central Michigan and the No. 2 overall pick in the NFL draft was starting to show glimpses of his potential.
"Having the chance to play football in Michigan, you heard a lot about Megatron," Brown said. "I've been a fan ever since. Had a chance to go see him play once when I was in college. What a great opportunity to come out here and watch him work."
When Johnson does his job for all to watch in the NFL's weekly showcase game, the defending Super Bowl champions and their fans may not like what they see.
Ravens rookie Matt Elam praised the 28-year-old Johnson on Wednesday, but also took what was taken as shots, calling him "pretty old," and saying the plan was to "make him uncomfortable," by getting physical.
"Sometimes you usually know the point where to keep your mouth shut," Johnson told reporters.
"He's a rookie. He'll learn. Hopefully this Monday."
The last time an NFL player uttered anything remotely construed as criticism of him going into a game against Detroit was in October when Dallas receiver Dez Bryant said he could do anything Johnson could do.
Johnson shrugged it off responded with his play. He had 14 receptions for 329 yards, the most by an NFL player in regulation, and a score to help the Lions win 31-30.
Baltimore quarterback Joe Flacco said Elam's comments made him shake his head, wondering why the safety said what he did.
"You just kind of look at him and say, 'Dude. What are you thinking? It's Calvin Johnson, man,'" Flacco said.
"It's kind of just funny that he put himself in a situation like that."
Johnson might get the last laugh when Matthew Stafford throws a deep ball to Johnson in Elam's direction.
"Yeah, we got to test him out," Johnson said.
The two-time All-Pro has 1,351 yards receiving — ranking second in the NFL, trailing Cleveland's Josh Gordon by 49 yards. He has caught 12 touchdown passes, behind only New Orleans tight end Jimmy Graham.
Johnson broke one of Jerry Rice's single-season records last year with 1,964 yards receiving. He also tied the Hall of Famer's personal mark with an NFL-leading 122 receptions.
"He transcends the position and is one of the greatest players of our time," Ravens coach John Harbaugh said.
"He is spectacular and he is a great person. I think he represents Detroit and the organization extremely well. I just think the world of him."