There is a conversation between Chris Evans & Ryan Reynolds. When Ryan suggested that Chris use cue cards, the latter turned down the suggestion and said he wanted to show up off-book. Does that mean he wanted to improvise in terms of what he was going to say?
Ryan was like, ‘Listen, if we need cue cards…’ and I was like, ‘Cue cards? I’m showing up off-book,'” Evans recounted. “I don’t get to say dialogue like this. Trust me. I’m going to enjoy every second of this. Memorized.
Off-book is a theater term meaning without a script in one’s hand, so by memory—and here meaning without relying on cue cards. Acting Studio Chicago provides an entry for the term in their glossary.
So to show up off-book means to arrive fully prepared with one’s lines memorized.
Paul Tanenbaum explained the actual words, but I think it's more understandable with some extra context.
The characters Chris Evans usually plays are known for being very politely spoken.
By contrast, Deadpool 3 has an R rating which means the script could include as much swearing and as many explicit jokes as the writers wanted. The writers took advantage of this and Chris Evans's character has a monologue with lots of strong language.
So with the context, a translation would be:
RR: Do you need help remembering your lines?
CE: No, I've already memorized them because I'm so excited about getting to swear and make explicit jokes, since I don't normally have strong language like that in my lines.
