Eagles fans want to be your dogs. (Justin Lane/EPA-EFE/Shutterstock)

The most whimsical sports totems usually arise for reasons that teeter between obscure and banal. The Los Angeles Angels’ Rally Monkey was born when the scoreboard operators decided to take a clip from “Ace Ventura: Pet Detective” and superimpose the words “rally monkey” over it. Florida Panthers fans once threw rubber rats onto the ice because Scott Mellanby killed a rat with a one-timer against the locker room wall. Boston Red Sox fans sing “Sweet Caroline” because the team’s game-day music coordinator liked the song and simply decided to play it one day.

There’s absolutely no mystery behind the latest craze, no somebody-decided-to-do-something-weird and it stuck. The Philadelphia Eagles have been underdogs throughout the NFL playoffs, so some of their players decided to wear dog masks. And now — with the team something of a surprise participant in this year’s Super Bowl — it’s a thing.

Despite a 13-3 regular season record and the fact that they were playing at home, the Eagles entered their playoff opener against the wild-card Atlanta Falcons as a 2.5-point underdog, mainly because Nick Foles was their quarterback instead of Carson Wentz. Foles had replaced Wentz after the second-year pro suffered a torn ACL against the Los Angeles Rams in Week 14, and while he had shown spasms of competence over his six-year NFL career, few thought he would be the one to lead the Eagles to never-before-attained glory. Three mostly meaningless games to end the regular season did little to change this opinion.

Philly beat Atlanta, 15-10, and afterward defensive end Chris Long and tackle Lane Johnson whipped out their authentic-looking German shepherd masks.

“I don’t know if you heard: There was a little narrative this week that the media was pushing that evidently we were like not favored?” Long told reporters afterward while wearing his mask. “So I [got] this mask. Somebody was like, ‘What’s up with the wolf mask?’ First of all, it’s a German shepherd. And it’s the underdog mask and I wasn’t going to field any questions, but I decided I would field them in the dog mask.”

Long and Johnson were supposed to walk off the field together wearing the masks. Alas …

“We were looking for each other, but I couldn’t find his scent,” Long said.

As told by Sports Illustrated’s Tim Rohan, the unofficially Philly-sanctioned masks can be purchased on Amazon from a Chinese retailer called CreepyParty, though it has had trouble keeping them in stock. The company quickly sold its entire inventory of 230 German shepherd masks after the Eagles beat the Falcons and then — after Philly was installed as a three-point underdog to the Minnesota Vikings in the NFC championship game — ran out again and again. Soon fans began purchasing other types of dog masks, and those began to sell out, too.

“If we [had] more, we [would have] sold 3,000 to 5,000 [masks],” Jason Lee, who runs CreepyParty, told Rohan.

The Eagles allowed fans to bring their dog masks to the Vikings game, as long as they took them off as they went through security, and the underdogs again had their day in a 38-7 mauling of Minnesota. The same rules will apply for the Super Bowl in Minneapolis, an NFL spokesman told The Post, which is probably for the best: Philly is somewhere around a 4.5-point underdog as of this writing.

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