Of course players sitting around the same table playing a game are going to be saying stuff that sometimes the characters being played by the players right next to them are not aware of. As a GM, there are a few ways to deal with this:

• You can enforce strict rules and separate the players so they can't communicate when their characters are out of contact.
• You can insist that players write down anything that should be secret from other characters and engage in note-passing to communicate with the GM.
• You can trust the players to faithfully separate player and character knowledge, and play their characters as if they don't know what the other players are thinking.

As a player, there is just one way to deal with this:

• Use every piece of player knowledge you can get your hands on to your own advantage.

Transcript

[SFX]: Pew Pew
[SFX]: Kabooom!
R2-D2: All right! Another hundred droids and I can level.
Anakin: Is that what you're doing? What about our mission?
R2-D2: Next level I can get Enhanced Environmental Sealing. I'm obviously not going to infiltrate an enemy HQ without that.
Anakin: It's so touching that you're into self-improvement.
{scene cuts to Jar Jar on the battlefield, surrounded by droids}
Captain Tarpals: Wesa done for, Jar Jar.
Jar Jar: Not yet! Here's da plan.
Jar Jar: Artoo issa very smart droid. Hesa can use da Trade Federation computers to tell da droids to stop working!
Captain Tarpals: But how yousa gonna tell him that?
{scene cuts back to R2-D2, shown in a moment of silence}
R2-D2: Oooh! I just had a brilliant idea! I hack into the Trade Federation's computer systems and spoof a shutdown command for the droid army!
R2-D2: Oh look, it's my best skill. I roll 10001.
GM: Er... There's no way R2 could know what Jar Jar thought of.
R2-D2: Do I sound like I'm talking in character?