PCs should exude confidence. After all, they are the heroes of your game world. Positive belief in themselves and their abilities is absolutely justified.

They should be confident that whatever they try will probably lead to disaster.

Transcript

Luke: I start dodging! 11!
GM: You evade Vader's shots.
Luke: We've got no time! Look, there's a hole in the grille. I can take it. I just know I can.
R2-D2: So, plan F then. Are you sure you don't want me to get Biggs to ram it first?
[SFX]: < dip-deep dip doip ni-poppy ping >
Luke: It's not gonna work. We'll be shot to pieces. Besides, I'm sure a shapeshifter would do a better job.
Wedge: You betcha, good buddy.
Luke: Biggs, Wedge, let's close it up. We're going in. We're going in... full throttle.
Wedge: Right with you, boss.
Biggs: Full throttle? Well, yeehaw! I bin savin' this bottle o' nitro moonshine fer jus' such an occasion.
Leia: Nitro the engines? Good idea!
Biggs: <glug glug> Huh?