Harrison Ford Famously Improvised His "I know" Line in E.S.B. (The Empire Strikes Back). Here are a few of his less-successful ad-libs:
[[Han Solo stands in front of Princess Leia on the Cloud City Carbon Freezing Chamber]]
Leia: I Love You.
Han: Well, Duh
[[Han Solo in the cockpit of the Millennium Falcon]]
C-3P0: Sir, the possibility of successfully navigating an asteroid field is approximately 3720 to 1!
Han: Seriously? ...Christ
[[Han Solo stands in front of Princess Leia on the Cloud City Carbon Freezing Chamber]]
Leia: I Love You.
Han: Oh! Hey, that explains the kissing earlier.

[[Han Solo stands in front of Princess Leia on the Cloud City Carbon Freezing Chamber]]
Leia: I Love You.
Han: I'm Nailing Your Brother.
[[Han Solo standing in front of Luke Skywalker, who is holding the blast shield helmet. The training droid hovers between them]]
Han: Hokey Religions and ancient weapons are no match for scissors, though they do beat paper and rock.
[[Han Solo stands in front of Princess Leia on the Cloud City Carbon Freezing Chamber]]
Leia: I Love You.
Han: Cool. Listen, this thing is really, REALLY cold.
[[Han Solo stands in front of Princess Leia on the Cloud City Carbon Freezing Chamber]]
Leia: I Love You.
Han: Wowzers.
[[Han Solo sits with two others. General Madine approaches.]]
Madine: General Solo, is your strike team assembled?
Han: Barely.
Han: They're pretty drunk.
[[Han Solo and Princess Leia stand in an Ice Tunnel of Hoth]]
Leia: I'd just as soon kiss a wookie.
Han: Man, me too, but chewie never seems interested.
Han: Maybe I should Grow My hair out.
{{title text: Oh, your brother is Luke. Sorry, should've mentioned that first.}}