This didn't happen to me, cause unfortunately I've never met any of them.
A friend of mine told me he was waiting for the band outside the venue here in Italy. At some point Jeremy came out and started signing something for him. While he was signing, my friend saw Josh coming out and began waving at him and shouting: "ZAC! ZAC!" to try to catch his attention He obviously knew he wasn't Zac, but he was so nervous he said the wrong name. And Josh gave him a bad look