You just destroyed the Death Star. You saved the galaxy and the Rebellion. Princess Leia loves you, and you don't know she's your sister yet. Galactic bliss. Now let's shotgun this beer and go home, kid.
We have no idea how or from where this fantastic behind the scenes vignette comes from. And yeah, maybe it'll make it a little harder to suspend disbelief next time you watch Episode IV—but you've gotta assume he was doing something before the big award ceremony.
But what if it had been in the movie? Would it even have changed anything? Surely they drink some kind of space beer. And those looks—the earnestness in Leia's eyes, the pride in Luke's. Why can't Lucas insert things like this into his interminable remakes? What kind of beer is that, really? Should so much thought be put into a GIF. Yes—forever yes.