The actress explained that she was a big fan of 1990s boybands as a youngster, including *NSYNC and its singer Justin Timberlake, who she currently appears with in sci-fi thriller In Time.
She told Jay Leno on The Tonight Show: "I did actually fake an asthma attack to get to the front of the concert, which is really not common for me. I was really claustrophobic and I was packed in with all these girls and there was a VIP area just feet away from me.
"So I screamed to my friends who were like three people back, 'Do you guys have my inhaler? I don't know where my inhaler is!' And then some security guard heard me, and picked me up and then put me in the VIP section of a Jordan Knight concert, thank you very much."
Seyfried added that she is currently building a ballet studio in her garage in order to gain more frequent practice.
"I always go to ballet classes in every city I work in and I'm always feeling really self conscious," she said. "I'm not a good ballet dancer. I just want to work more on my posture and my turn out, and there are all these little girls in it and they would recognise me and I'd embarrass myself, and the classes here in LA - they're all professionals."
The Mean Girls star was rumoured to be dating real estate executive Andrew Joblon last month.
> Amanda Seyfried: In Time will leave you breathless'
Watch the trailer for In Time below: