You know and love classic "Saturday Night Live" characters like Debbie Downer and Target Lady, but how did they come to be? In a Glamour magazine piece featuring interviews with more than a dozen current and former "SNL" cast members, Tina Fey, Rachel Dratch, Kristen Wiig and Kate McKinnon shared their inspirations for some of their most fondly remembered characters.

Here's how Target Lady, Debbie Downer and more were born.

Tina Fey: Mom Jeans

"I was complaining about my unfortunate jeans with Amy, Maya, and Rachel. Somebody called them mom jeans, and it turned into the [classic Mom Jeans ad]. Looking back, I'm at my goal weight in that commercial, even though I was wearing padding."

Rachel Dratch: Debbie Downer

"I was on vacation in Costa Rica, and when I told someone that I was from New York, they asked, 'Were you there for 9/11?' The conversation froze. When I got back, the name [Debbie Downer] popped into my head."

Kristen Wiig: Gilly, Target Lady and Penelope

"Gilly [the pesky schoolgirl] started with a silly face I made working late at the show one night. Target Lady was in fact inspired by a Target worker. Penelope came from listening to someone one-up people all the time. We all know a Penelope or two."

Kate McKinnon: Justin Bieber

"I was asked to play Justin Bieber, but didn't think I could—it was a torturous week. I watched a ton of videos and practiced his footwork, but it's complicated, so I went with his smirks."

For more character origin stories and tales of "SNL" shenanigans, head to Glamour.