The football adage that the most popular guy in town is the backup quarterback doesn’t apply to the Giants.

The most popular guy — at least among a portion of the win-starved fan base — is the backup to the backup quarterback.

Tuesday marked the one-year anniversary of Tommy DeVito’s first NFL touchdown pᴀss, which was the beginning of the tristate mania that injected life into a ᴅᴇᴀᴅ season for the Giants.

As an undrafted rookie raised in Cedar Grove, N.J., DeVito made six starts and developed a cult following that formed huge autograph lines at his appearances and copied his Italian-roots homage pinched-fingers touchdown celebration.

“It was a roller coaster, but it was a ton of fun,” DeVito told The Post. “It hit me most at Christmas, where I probably got tagged and messaged, no joke, about 500 times with pictures of little kids opening my jersey. Parents are sending them to my parents. That was probably the coolest part for me.”

DeVito, 26, hasn’t taken a snap or been activated for a game this season. If the Giants bench Daniel Jones — the $23 million injury guarantee in his contract combined with a 2-7 record soon could force their hand — Drew Lock is up next.

The Giants have started the process of moving on from Jones after the season, but both Lock and DeVito are free agents.

Lock is a trusted veteran backup with 23 career starts. DeVito, who moved out of his parents’ home in the offseason, is confident he will get another chance to start somewhere in the future.

“I feel good about it,” DeVito said. “My mindset, my work ethic, the way I’m going to keep progressing as time goes on, it’s only going to make me better.”

For now, DeVito is working behind the scenes to make sure that he is ready if opportunity knocks again over the final eight games.

He asked a question in Friday’s meetings that made quarterbacks coach Shea Tierney see a different argument to an offensive concept versus a specific defensive coverage.

“I started off in college playing in the black and white,” DeVito said. “I think in the NFL you have to play in the gray, especially at the quarterback position. Not everything is going to be clean. You have to be able to operate when things are bad.

“That gives me that ‘F it’ playing style from time to time. Whether it be here or another team, whenever it is in the future, I think you still need to have that chip and that edge about you — but continue to learn more between the ears and make good decisions.”

DeVito completed 72.2 percent of his pᴀsses with five touchdowns and no interceptions during a three-game winning streak against the Commanders, Patriots and Packers.

The magic wore off, the Giants turned back to Tyrod Taylor and DeVito went to work with tape to correct issues such as taking 37 sacks on 215 dropbacks.

“My biggest thing from the offseason was, ‘Get the ball out of your hands and find something to do with it — throw a checkdown, throw it away,’ ” DeVito said. “Keep the offense in good situations. That’s something I want to continue to build while keeping that gunslinger personality.”

Even though he is not on the field, DeVito is not out of the spotlight. He recently was mobbed at a Yankees playoff game — forgiven by anyone who naively expected the Giants to tank last season to draft Jayden Daniels or Drake Maye.

“I think it’s mainly because I bring a little excitement when I play and a different type of energy with the way I carry myself,” DeVito said. “But I know how it is: Everybody loves the backup quarterback because they have nothing to lose and they aren’t expected to do this, that and the other thing. I just try to give it all for the fans because they are the ones who pay to come watch.”

Head coach Brian Daboll does not give 11-on-11 reps in practice to Lock or DeVito during the season.

DeVito gets throws in individual drills, runs the scout-team offense and has adopted the veteran Lock’s strategy of copying Jones’ script after practice with receivers who stick around for extra work.

“The old cliché in the quarterback room is ‘You are one snap away from being the starter,’ ” Tierney said. “People say it. Not many people live it. But he did. He was ready. It wasn’t too big of a moment. I was proud of Tommy then, and I’m proud of him now of how he’s handled this situation. He’s still developing. He goes out every day trying to learn. He has a good way of seeing the game for asking good questions.”

Because the Giants quarterbacks are тιԍнт-knit — Lock has been a huge resource in DeVito’s development as someone who has been a starter, a backup, booed, cheered and forced to learn several different offensive schemes — a third-stringer can hold the others accountable and vice versa without anyone feeling threatened.

That’s not the case everywhere in the NFL.

“You stay the course because you don’t know when your name is going to be called,” DeVito said. “Same as last year, but a little different because I didn’t know I was going to play. I went through that last year so now I know it’s a real thing. I’ll keep my head down and when the opportunity is there, make the most of it.”