(CNN) -- In the grand history of celebrity mugshots - which includes Nicole Richie's smizing and Paris Hilton's "did you get my good side?" head tilt - Bruno Mars' September 2010 photo is a standout.
The "Locked Out Of Heaven" singer had been booked on a drug charge in Las Vegas at the time. Instead of doing the stoic face of someone in trouble with the law, Mars smiled like he was at the Grammy Awards.
When GQ magazine, which hosts Mars on the cover of its April "Style Bible" issue, asked the singer why he was grinning upon his arrest, Mars couldn't quite say.
"I have no idea," he responded, laughing. "It was a picture."
It's also one image that Mars would like to forget. As he told Piers Morgan last year, he's been trying to move forward ever since his arrest.
"I was really intoxicated. I was really drunk," Mars recalled to GQ. "So a lot of that is a big blur, and I try every day to forget and keep pushing."
So far, his attempt to leave the past in the past is working. Mars just notched his first No. 1 on the Billboard 200 chart with his 2012 album, "Unorthodox Jukebox" - not an easy task, he said.
"You know how hard it is to write a big song? That s*** is hard, man," he admitted to GQ. "I don't ever want to come out with something safe and get away with 'It sounds good!' It's got to be more than sounding good. The music I like are events. ... 'Bohemian Rhapsody' is my favorite song - that song's an event. And that's what I want to do. I'm sure that shocked the world, that song. 'Billie Jean' shocked the world. 'Smells Like Teen Spirit.' Those songs are events. That guy put everything he got into that, and he meant it."
But even with that intention, there are moments when Mars' own work catches him off guard.
"('Locked Out of Heaven') shocked me. That it turned out the way it did," he told the magazine. "I haven't done a song like that. And hopefully every album, I'll get that feeling. And shock the world!"
So he wants to shock the world, GQ asked?
"Hell yeah!" Mars responded. "I've got nothing else to do."