Troy Aikman Shows Off Arm In Viral 'Eight Can Challenge' Video

Watch out, Dak Prescott and Cooper Rush ... Troy Aikman showed he's still got magic left in his right arm -- knockin' down 12 beer cans with two, pinpoint 20-yard throws!!

The Dallas Cowboys legend hit a field in Texas to complete the feat -- and while he tells TMZ Sports the footage might not be "100 percent" real ... he did say the accuracy he showcased in the vid is legit!!

"That was my strength, you know?" the 55-year-old said with a laugh.

Troy performed the stunt in hopes of igniting a viral craze -- where people think of creative ways to knock down pyramids of EIGHT Beer cans -- that will benefit a great cause.

Aikman dubbed it the "#EIGHTBeerChallenge" -- and he said for every one person who participates in it, films it, and shares it to social media, he and his beer co. will donate $8 to Back On My Feet, an org. created to combat homelessness.

"It gives a chance for some of the homeless people in the community to be empowered," Aikman said, "and to get them back on their feet, being an active participant in society, doing a lot of different things."

Aikman said he's planning on showcasing some of the best vids of the challenge on his social media pages over the coming weeks.