I had been to Red Sox-Yankees games at Fenway Park many times, dating back (believe it or not) to when Ted Williams and Mickey Mantle were playing. Seriously. I probably still had diapers on, but I was there. I've also been to Red Sox-Yankees games at both the old and the new Yankee Stadium. I had observed how fans of either team behave at both places, but I had never been in the position of looking like a Yankee fan at Fenway.
Yankee fans are more likely to be loud and obnoxious.
Too many of them wear loud, garish Yankee gear. When a Yankee player does something at Fenway you can count on a bunch of Yankee fans jumping up and making a big deal out of it. "CC...way to throw a strike!" or "Hip hip Hor-HAY" or "The Melk-man dee-livvers." This is more than cheering, it's loud. They stand up to do it, and stay standing way too long, blocking your view. It's probably intentional. Shut up and sit down.
Red Sox fans are more likely to behave.
On the other hand, Red Sox fans at Yankee Stadium are more likely to wear a simple blue cap with a red B. Maybe a Mike Lowell shirt. They'll sit there and enjoy the game quietly. Of course, this might well be caused by fear of getting their ass kicked.
At a party.
Yankee fans love to talk about The Babe, Bucky Dent, Bill Buckner and Aaron Boone. They love to flaunt their 26 World Championships and laugh about how we waited 86 years. Do they have a decent response if you point out that 18 of those 26 happened over 50 years ago? That 22 of those 26 were over 30 years ago? That the last three Yankee wins happened in the steroid era? No, they don't.
Ah, yes...the steroid era.
During the game in New York, one week after the news about David Ortiz broke, he got the expected hoots, although nothing worse than A Rod, Damon or Gary Sheffield have gotten at Fenway. One guy kept calling him "Big Popup." Of course, Ortiz did nothing to shut the guy up, popping up three times. He also grounded out and hit into an inning-ending double-play.
Here's what got me. When Ortiz would come up they'd hold up signs that said 1918, 2004*, 2007*. Really? You want to talk asterisks? Let's look at the last ten years...1998 through 2008, including the last two times the Yankees won the World Series and the two most recent Red Sox wins. On the Red Sox side of the ledger you've got Papi and Manny on the list. What about Yankees during that period? Got your pen ready? There's Ricky Bones, Rondell White, Jason Grimsley, Chuck Knoblauch, David Justice, Jose Canseco, Glenallen Hill, Jim Leyritz, Randy Velarde, Denny Neagle, Mike Stanton, Kevin Brown, Aaron Boone, Matt Lawton, Ron Villone, Gary Sheffield, Jason Giambi, Andy Pettitte, Roger Clemens and A Rod. That's 20-2, bad guys.
Yankee fans are worse. Your witness.