Obi-Wan is displaying a high level of talent in the skill of "Fast Talk the GM". The technique used here is to (not so) subtly point out that any reasonable and intelligent person would have to agree with whatever insane and unworkable idea the players are proposing, rather than the carefully designed and crafted setting and rules details that the GM intended.

And then, just when it looks like it's not going to work, he pulls out the master stroke.

This comic aims not only to entertain, but also to improve your own roleplaying technique. Just don't let your GM see it.

Transcript

GM: The droids fire!
Obi-Wan: We're screwed.
Qui-Gon: I block the shots with my laser sword!
Obi-Wan: What?
GM: What?
Obi-Wan: No... actually... that's going to work. A laser sword has to be a magnetically contained tube of plasma. Anything else is clearly ludicrous.
Obi-Wan: The containment field would obviously work in both directions. A blaster shot is also plasma. Q.E.D.
Qui-Gon: So... it'll deflect the shots back towards them?
Obi-Wan: Precisely!
GM: Who's running this game? No way!
Obi-Wan: Oh, well then, I guess we die and your campaign ends.
{beat}
GM: <grumble> Okay, make a Parry roll.
Qui-Gon: 18!
{blaster bolts get deflected and droids get chopped to pieces}
[SFX]: Krtzang!
[SFX]: Whooom!
[SFX]: Whooom!
[SFX]: Krtzang!
{fight is over, dead droids litter the floor}
GM: I can't believe I let you get away with that.
Qui-Gon: I take all the blasters!