"Just got kicked out of the Chargers stadium and couldn't be prouder! Go Cincy Bengals!" he tweeted. "I'd talk trash to everyone in SD, but what's the point? you already had me kicked out of the stadium and you still lost."
The Bengals beat the Chargers 20-13.
On Monday, Lachey, 39, explained, "Majority of Charger fans were awesome yesterday, thanks for the hospitality! Sadly, there is always one guy that ruins it for everyone . . . "
"For the record, I was not kicked out of the Chargers game for excessive 'trash talking.' No, that honor belonged to the guy in front of me!" Lachey tweeted. "I simply don't appreciate someone turning around and putting their finger in my face. Call me crazy, but that deserved a reaction."
He added, "Again, aside from a few exceptions, I had a great time hanging with Charger fans all afternoon. Honestly, some of the nicest fans around."
Lachey, who welcomed his first child, son Camden with wife Vanessa Lachey on Sept. 12, recently told Parade magazine that he bonds with his son over football.
"Now with Camden, he has his own Bengals onesie and the team is 3-1 with him cheering them," the new dad gushed. "So in the last month, my tradition has been changing him and getting him ready for football at 10 o'clock. Then we sit together and watch. It's awesome."