Play a team in your own division three times in a season, and things get that way.
That's only the start, though.
Add in the 95-mile trek up or down the New Jersey Turnpike and the fact that today's game will be the eighth between the teams in the past three seasons, and this rivalry can get downright nasty.
"There's a strong dislike for one another," Giants All-Pro guard Chris Snee said. "Anytime you get a chance to knock out a divisional opponent, one you don't like, you get geeked up for these challenges. I think both sides would agree that to knock the other out would make the other one happy."
There is another element that will add to the intensity. The NFC semifinal at Giants Stadium matches the defending Super Bowl champions against the team that many think will be the 2009 version of the New York Giants.
"I don't think anybody has to do anything to get up for this game," Giants cornerback Corey Webster said. "I think it is already built up. Everybody knows what is at stake. I just think every team is going to be prepared and ready to go and they are going to be very excited and our guys are going to be up for the challenge this weekend."
Of the seven previous games during the past three seasons, only two have been decided by more than 10 points, with the largest margin being 14. The two games this season were decided by a combined 11 points. New York (12-4) won 36-31 in Philadelphia and the Eagles (10-6-1) returned the favor at Giants Stadium 20-14 on Dec. 7.
"I think the guys all know each other and everybody knows each other's number, jersey number, and all that bit," Eagles coach Andy Reid said. "But every game is different and if you come in saying you know the New York Giants, I think you make a huge mistake in the process of getting ready to play them."
The Giants come in as somewhat of a question mark. They won 11 of their first 12 games, and then lost three of four in December. Their only win was an overtime decision against Carolina which wrapped up the conference's No. 1 seed in the penultimate week.
Adding to the team's woes was the season-ending suspension of Plaxico Burress in early December after the receiver accidentally shot himself in the thigh at a New York City nightclub. Without Burress, the Eagles played the safety closer to the line of scrimmage in the last game and held New York's league-leading rushing game (157.4) yards to 88 yards.
Eagles QB Donovan McNabb wanted no part in a comparison between the Eagles of this year and last year's Giants, who got hot late in the season en route to a title.
"It's easy to say that at this point," McNabb said. "We just want to kind of be the Eagles of 2009. I mean, it's easy to sit back from afar and say that, but I don't see it right now."