"If there's somebody getting out of line, cussing, swearing, we call the police and have them taken out of here because we don't want to screw up what we have going," said Roger Pineda.
He has been tailgating since the 1990s and said some booze and some fan arguments can lead to trouble.
Toward the end of last football season, police received complaints about fan-on-fan violence and harassment in and out of CenturyLink Field, some of which was witnessed first-hand by officers attending games while off-duty.
One of those episodes involved two off-duty Bellevue police officers who used profanity at a uniformed Seattle police officer and stadium workers and were later escorted out.
This season, undercover Seattle police officers will be milling about in the crowds at Seahawks home games, starting with Thursday's pre-season game against the Oakland Raiders, looking for bad behavior on game day.
"It's just extra eyes to make sure that the area around CenturyLink is safe," said Sean Whitcomb with SPD.
Whitcomb said officers will be looking for people taking team rivalries too far by threatening, intimidating or harming other fans.
Raiders fans know their reputation though. A large group from a northwest fan group descended en masse before the game.
Dana Siplin was leading the charge and didn't want any sort of attacks on either side.
"Everybody likes to root for their team. Everybody wants to be a part of that fanfare. But we're just tired of all the violence," he said.
Siplin and others are part of "Fans Against Violence," a group that tries to pull back the "Black Hole" stereotype of Raiders fans to make sure families can feel safe at any stadium.
"We're tired of our kids getting hurt," Siplin said.
Whitcomb wouldn't say how many officers would be undercover but they are allowed to make arrests if need be.
He just isn't sure how to break it to them that they will have to wear San Francisco 49er jerseys in two weeks.