Every good plan rests on attention to detail.

When infiltrating the lair of an orc horde, you want your barrels to be full of rough beer, not fine wine. And vice versa for elves.

Just don't ask what the barrels are for.

Transcript

Obi-Wan: ... okay. <sigh> Then I collect the Orb—by myself, with my bare hands—and meet you all back at the ship.
R2-D2: Threepio and I will guard the ship.
C-3PO: Somehow. For some reason.
Luke: Han, Chewie, and I are going to the detention cells to rescue Princess, right?
Han: Exactly!
{beat; skeptical looks from Obi-Wan, C-3PO, R2-D2, Chewbacca, and Luke}
Han: Oh, I know why you all think the plan couldn't possibly work.
Han: I forgot to mention that we're all going to the cell block in handcuffs!