Deep inside the Metrodome, far from the Astroturf upon which he regularly makes dazzling catches, Luis Rivas is biting a pillow. Rookie third baseman Terry Tiffee straddles Rivas, pummeling his head with a Twins logo-embossed throw pillow — standard issue to newcomers to the perennial AL Central champions. When people discuss the success of the Twins, they often credit it to the team’s pitching and defense. In reality, manager Ron Gardenhire says, it can be chalked up to an old-fashioned Midwest staple: nightly pillow fights.

“Some teams get pumped up with music, others speeches,” says Gardenhire. “For us, it’s more old-fashioned: we strip to our skivvies and beat each other senseless with pillows. It keeps the kids from thinking too much.”

As members of the Twins readily point out, pitcher Johan Santana’s amazing run last year only began when he KO’d Shannon Stewart with a pillow husband to the solar plexus. With that victory, he became unstoppable, and remained undefeated for the rest of the season.

Young members of the Twins — called Twinkies by the veteran players — often have a hard time adapting to Minnesota baseball. Early last season, rookie catcher Joe Mauer declared the pastime “gay” to a member of the front office. Later that night, his knee was pummeled with a doorknob-filled pillow as retaliation. Not even the budding superstars are allowed to eschew the tradition, as Justin Morneau learned thanks to a serious concussion earlier this season.

The Twins pillow fights are serious business. Reliever Juan Rincon admitted to a friend on the team that his steroid use — for which he received a 10-day suspension — was solely to improve his weak showings during the early-inning Swedish neck pillow bullpen brawls, which earned him the “soft” tag among the pitching staff.

But now the tradition could be facing extinction.

Pitcher Terry Mulholland was injured on Monday when Brad Radke’s trusty lumbar support weapon exploded with a smack to Mulholland’s face, sending feathers across the clubhouse, including one into the veteran pitcher’s eye. It’s unclear when he will be able to return.

While members of the Twins organization take it in stride, Senator Norm Coleman (R-Minn) was incensed to learn of the practice and how it had derailed Mulholland’s 2005 season. “This isn’t baseball,” Coleman said on the Senate floor, “this is some liberal sorority party.”

Whispers on Capitol Hill say that Coleman is considering attaching a rider to John McCain’s anti-steroid legislation that would ban “any form of recreation involving pillows or other soft objects.” The bill has a legitimate shot at passage, say Washington insiders.

Ron Gardenhire, for one, will fight it tooth and nail. “They say they don’t want to be soft on sports,” he says, “but if [Coleman] doesn’t watch it, he’ll wake up to a mouthful of feathers.”

Joe Christensen is a columnist for the Minneapolis Star-Tribune.