With reporting by Michael Pell

Amanda Seyfried learned a very invaluable life lesson on the set of "Ted 2": don't f--k with Mark Wahlberg.

"Yes, I f--k with people," Seyfried told MTV News at the London press day for their upcoming flick "Ted 2." "I really do. My sister and I are impulsive hiders and startlers. I'm trying to cut down, but I just can't help it."

So, what happened when the notorious prankster messed with one of Boston's finest? Nothing good, that's what. Seyfried's adorable pup Finn was put in a very precarious situation. Let Seyfried and Wahlberg give you the deets:

"She'd like sneak up on me and scream as loud as she could in my ear," Wahlberg explained. (Not cool, Seyfried. Not cool.) "I like to take naps, I'm old."

Seyfried's punishment for messing with Wahlberg's nap time? "I kidnapped her dog," he said, "And she never messed with me again."

Seeing how close Seyfried and Finn are, it's safe to say the experience absolutely traumatized the actress. "Oh, that's true," Seyfried confirmed. "Traumatic and true."

"Ted 2" hits theaters on June 26.