When actors get cast for secret roles in coveted films like, let's say, Solo: A Star Wars Story, they have to sign a non-disclosure agreement which prohibits them from telling others about it.
"Well you have to tell your family," he said on Jimmy Kimmel Live! "So I told her [his grandma] and you're scared that it's gonna get out or that you leak it and get in trouble or something, so I was very clear with my nana about don't tell anyone that this is happening and I called her a week later and she was like 'my friends are so excited. Everybody can't wait.' I was like 'Nana, you can't' and she was like 'well that's ridiculous.'" (To be fair, even Ehrenreich had a slip up.)
Luckily it seems his nana doesn't know much about the Star Wars franchise so it's possible she may have told her friends it was Star Trek instead. Ehrenreich told Kimmel he's bringing his grandma to the premiere. Although she "doesn't really care about Star Wars," she's a "real big fan of [him]."
"She calls it Star Trek and she can't remember Chewy's name, she says 'oh that big hairy, what's the big foot guy or the bear or something.' But yeah, she's very excited," he said. Grandma FTW. (Although, he should probably sit her down for a no spoilers talk.)
Solo: A Star Wars Story arrives in theaters on May 25.