The members of Sum 41 all look like they're twelve years old, except the bassist -- he looks like he's eleven. But somehow, they exude innocence even when they're talking about drugs and strippers. Four Canadian kids who grew up in the humble town of Ajax, Ontario, they now tour the planet and party down together. As any Canadian will tell you, there's small-town boredom, and then there's Canadian small-town boredom; the wide open spaces of the Great White North lend themselves to the rock & roll excess that only the world's most boring places can inspire. Sum 41 know a lot about excess.

"We're basically four guys who've known each other our whole lives," says singer-guitarist Deryck Whibley. He, bassist Cone McCaslin, guitarist Dave Baksh and drummer Steve "Stevo32" Jocz are all twenty-one or twenty-two. They got together straight out of high school, having played in all the different local punk bands, and hit the big time in 2001 with their 3 million-selling pop-punk debut, All Killer No Filler. The snotty hit "Fat Lip" was full of rowdy guitars and whiny rapping; it established Sum 41 as the missing link between the Beastie Boys of Licensed to Ill and Blink-182. Their metal-tinged new album basically sums up their approach to life: Does This Look Infected? How Canadian are they? Jocz has a cousin who named his two sons Geddy and Alex, after two-thirds of Rush.

Only Canadian kids could still sound so wholesome while spinning such depraved road stories. For instance, just the week before we meet in New York in early November, there was the little episode in Tokyo with the liquid LSD. "We were drinking at Lexington Queen, this bar in Tokyo," Jocz remembers. "The last time we were there, we were all high on mushrooms, because they're legal in Japan. So this time, me and Deryck went to this head shop across the street and said, 'Gimme the strongest thing you got.' And he gave us four vials apiece of liquid acid. I was on my third vial before we realized what it was. There was this big poster of Scooby-Doo. We stared at it for about an hour, terrified. And everyone said, 'Steve, go up and touch it to make sure it's not real.' So I went and touched it. It was just a poster, but we were so scared. Never again!" Right now we're on our way to a Knicks game at Madison Square Garden, with prime courtside tickets. Despite the fact that Sum 41 are conspicuous as the only spiked-hair punkers in the Garden, nobody pays much attention. The only recognition comes from a middle-aged security guard who jerks his thumb and says, "Hey, what's my age again!" (Wrong band, dude, but an A for effort.) "Nobody notices us," says Baksh, the band's Guyanese guitarist, whose tax forms probably list his occupation as "the quiet one." "Nobody ever notices me. They don't know whether I'm Dave from Sum 41 or Tony from No Doubt." The Knicks game is a bore, and we spend most of our time there talking about music. Jocz is excited to be in Madison Square Garden because it's where Sly Stone had his wedding onstage in 1974. Whibley, who looks like Chris Isaak's Mini-Me, grew up in Ajax with his single mom, obsessed with rock & roll. "I used to form bands with my G.I. Joes," he says. "I would make them sing Beatles and Monkees songs." When he hit his teens, he discovered Nirvana and punk rock. "I was a Kurt kid. I had the hair; I had the cardigans. And that's when I started writing songs."

Sum 41 hits such as "Fat Lip" and "Motivation" goof on teen angst, but on Infected, Whibley has grown more thoughtful. " 'The Hell Song' is about a friend of ours," he says. "She just found out she has HIV. It's, like, the first really serious thing to happen in our group of friends." But Whibley seems horrified at the suggestion that Sum 41 are growing up, even though they're now all homeowners.

At halftime, a few kids sneak over for autographs, prompting the Knicks' official celebrity photographer to ask for a few shots. "Uh . . . " he asks Whibley, "would you mind putting the beer down for a minute?"

After the Knicks game, sum 41 head for the Paramount Hotel bar. They fondly remember this place -- the last time they were here, they got thrown out when they got drunk and tried to sneak one of the lobby chairs up to their room. This is also where the band stayed on McCaslin's twenty-first birthday. "That was the night I puked on Nikka Costa," he remembers. "We were at this MTV party, I was on mushrooms, and the whole room started spinning. Nikka and I were talking about music, and suddenly I just went bleeewaaaagh on her leg. I felt terrible about it. But I think she understood." Not all their drug experiences have been happy ones. "Poppers," says Jocz with a shudder. "Amyl nitrite. I was hanging with this drug dealer, sampling a bit of everything he had: a little coke, a little E, the whole thing. And he had these poppers. You inhale it, and it makes you feel so good. And it screwed me up for months. I was stuttering, forgetting what I was about to say. Messed up my head."

Despite all this road debauchery, McCaslin and Baksh stay faithful to their long-term girlfriends. So how do they hold it down on the road? Says Baksh, "Thanks to Vivid Video and Private Productions, I hold it down pretty good." When they ask me where I'm from, and I tell them Boston, they look at each other and laugh. "The mobile strip club!" Jocz says. "That was Boston. We were at this boring industry party, and these two girls came up to us, and we could tell that these girls were not music-business people. They were . . . " "Them," McCaslin says.

"They were them," Jocz agrees. "One said, 'Hello, my name is Isis, and this is my friend Ecstasy.' And I figured, 'Hey, an Egyptian goddess and a designer drug. We're good to go!' " Shockingly, the girls turned out to be strippers, and they lured the boys into their customized Winnebago, which had a pole and strobe lights. "We rode the Winnebago all around Boston. Isis was great -- she was in the middle of giving me a dance when she got this call on her cell phone. It was her boyfriend, and I guess he was totally pissing her off, because she took her heels and started jamming them into me so hard. She was pissed at her boyfriend and taking out all her frustrations on me. And I'm into that."

After a couple of beers, two old friends from back home stop by. One is their road videographer, Shamus; the other is Matt, the drummer from Avril Lavigne's band, which is in town for a show and staying at the same hotel. Matt and Shamus have just come from a local deli, where they bought their own beers to sneak into the bar.

All the guys crowd around a table, cracking private jokes about high school. There's some gossip about Canadian bands they hate, and then they start making plans for when they're all back in town for Christmas, sounding like college kids planning for winter break. Everyone wants to be home by the twenty-third, because that's when Whibley's mom throws her Christmas party. Her parties are famous -- last year, an old metalhead hit on McCaslin's sixteen-year-old sister and then told McCaslin's mom to fuck off when she intervened.

Sum 41 may be raising hell around the globe, but the party doesn't even stop when they get home. As Whibley says proudly, "Our parents party harder than we do."