Hamm and his former costar John Slattery marked 10 years since the series' finale with a panel at ATX TV Festival and shared some behind-the-scenes secrets

When the younger cast told Hamm they "wanted to feel" the burn of real cigarettes, the series star joked, "Let me know how that goes."

Jon Hamm recounted having to smoke so many fake cigarettes and drink onion water 'vodkas' on 'Mad Men': 'Oh, the breath was lovely!'