Charlie Day is not a method actor; he’s more of a what you see is what you get kind of guy. The characters he’s best known for — Charlie Kelly on “It’s Always Sunny in Philadelphia” (for which he also writes scripts) and Dale Arbus in the two “Horrible Bosses” films are excitable fellows, ever-ready to burst into a high-pitched reactionary rant when things don’t go exactly as planned.

That’s what’s funny as well as charming about the people he plays. And though those roles are a bit exaggerated, Charlie Day, in person, is also apt to go all squeaky and wide-eyed, especially if he gets a question that, well, excites him. Day, 41, was in Boston earlier this week to talk about his new comedy “Fist Fight,” in which he plays Andy Campbell, a mild-mannered high school teacher who is challenged to a parking lot scrap by another teacher, Mr. Strickland, played in volatile style by Ice Cube.

Q: How did you get involved with this film?

A: I was halfway through a season of “It’s Always Sunny in Philadelphia,” and I knew I had a hiatus coming up. So I called my agent and asked if there were any scripts floating around that might need a rewrite, something I could brush up. He said this movie “Fist Fight” just came over his desk, he gave me the pitch, and I thought it sounded interesting. So I had him send it to me, I read it, and the script was in pretty great shape. I called him back the next morning, and said, “I want to do it. I want to be in it.”

Q: How would you describe your character?

A: Andy Campbell is a very affable guy. He’s allergic to confrontation, he tries to kill people with kindness, and he’s a bit of a pushover. He’s a very loving father, he’s a caring teacher, and he’s having the absolute worst day of his life: The school is making cutbacks so he may lose his job, his wife’s about to have a baby, the students are running all over the school, and he happens to get in the middle of a confrontation that Ice Cube’s character is having with his students. (Day’s voice noticeably goes higher at this point.) And he’s given a Sophie’s Choice of either pointing the finger at Ice Cube and saying this man deserves to be fired, or losing his own job. A very unenviable position. It’s a tough day for Andy Campbell.

Q: There is, of course, a wild climactic fight. How did you prepare for that scene?

A: I didn’t prep enough for it, I’ll tell you that much. I mean, when you make “Rocky” or “Rocky 2, 3, 4, 5,” you’re probably in the best shape of your life. Andy Campbell, of course, cannot be in the best shape of his life, otherwise the movie doesn’t quite work. If I got really ripped for this movie, I think it would undermine the character. So I was given a very rudimentary lesson on how to make a fist (laughs) and I learned some of the choreography, then (director) Richie Keen put me through eight days of sheer hell. It took eight days to shoot that fight. I can’t tell you how many times I got thrown into that school bus. There did come a time in the filming when I could no longer feel my left foot. Still, on a rainy day or if I walk too far, I have some aches and pains from doing this movie. And Cube doesn’t like to admit it, because he has a tough guy persona, but he got banged up pretty good, too. You know, we didn’t want to do a movie called “Fist Fight,” and you get to the end and you’ve been watching two stunt doubles fighting all the time.

Q: Who made you laugh as a kid?

A: I love the Monty Python guys. The first time I saw “Holy Grail,” that really got me. I loved Chris Farley. I saw “Tommy Boy” a hundred times. Early Jim Carrey, Gene Wilder, Richard Pryor, Peter Sellers. I loved the Pink Panther movies. And Woody Allen. I go back and watch “The Purple Rose of Cairo” all the time.

Q: When did you make the decision to be an actor?”

A: I was always the class clown, I loved to make people laugh, and I did plays as a kid. But I really got into baseball. I wanted to be playing for the (Boston) Red Sox. I played a lot in high school. Second baseman, of course. The little guy position. But when I got cut from the team in college, I joined the school theater troupe. And it came so much easier to me. I always had to prove to people that you could put me in the game and I was gonna do all right, but this was the first time people said, “Oh, I want you in the play.” Everything changed. And oh, by the way, girls started paying attention to me.

“Fist Fight” opens on February 17.

— Ed Symkus writes about movies for More Content Now.