Worst celebrity encounter?
We once brought a tiny monkey with us to a show. We ran into Shakira, and she was like, "Ooh! Can I pet him?" Then the monkey bit Shakira.
Fall Out Boy Scores Third No. 1 Album on Billboard 200
Have you ever brought your mom as a date?
I brought her to the preparty when we were up for the best new artist Grammy in 2006. She met Jay Z. He took off his sunglasses when he met my mom, which was a very good lesson in humility. Then we didn't win. I was mad, and at the afterparty, my mom made me introduce her to Sting. It took my mind off losing.
Ever played an awards show intoxicated?
I've never performed intoxicated, but I've gone buzzed. I remember one time sitting next to Nathan [Williams] from Wavves, and he was like, "Dude, I just dropped acid." I was like, "Oh, my God! You dropped real acid?" It was the worst possible environment. His exact line back to me: "Who the f-- drops fake acid?"
Here Are Fall Out Boy's Ten Best Songs
Did you check in on him throughout the night?
No, but there was a point where Odd Future had won an award. I looked over, and Nathan was hugging Tyler [The Creator]'s mom over and over again. I was like, "This is so weird."
Watch The Billboard Music Awards: An Insider's Guide sneak-peek special on Saturday, May 16 at 9 p.m. ET on ABC and the 2015 Billboard Music Awards on Sunday, May 17 at 8 p.m. ET on ABC.
This story originally appeared in the May 16 issue of Billboard.