How I Met Your Mother’s successful run was dependent on a decade-long secret that David Henrie kept concealed.

The Wizards of Waverly Place actor recently shared a funny story on The George Janko Show podcast about fans trying to bribe him with free drinks to spill the details of the show’s finale.

“By season 6 or 7, I’d turned 21, and people would be like, ‘We’ve heard you know the ending!’” Henrie recalled. Fans would send drinks his way in hopes of loosening his lips, but he had signed a nondisclosure agreement (NDA) early on and wasn’t about to risk breaking it.

Henrie, who played Ted Mosby’s son on the CBS sitcom, revealed that the show’s creators, Carter Bays and Craig Thomas, shared their plans for the finale with him and co-star Lyndsy Fonseca during season 2. To avoid the actors ageing noticeably over the nine-year run, producers filmed stock footage of Henrie and Fonseca early on—also locking them into a secret about how the series might end.

“They brought in NDAs and said, ‘We gotta get back to Robin somehow,’” Henrie explained. Despite offers and pressure, he kept the secret for nearly eight years, determined not to get sued.

“I didn’t tell a single person,” Henrie said proudly, holding strong to his iron-clad agreement.