Describe Joe's visit to Pip in London.

Pip is positively dreading Joe Gargery's imminent arrival. The young man's moving in fashionable circles now, and as he openly admits, he's become something of a snob. So when Pip finally catches up with his old friend in London, Joe's unwelcome presence acts as an uncomfortable reminder of the humble life he once lived on the Romney Marshes.
Poor old Joe's completely out of his depth in the big city. He's just a simple country blacksmith and behaves even more awkwardly than usual in his new surroundings. To make matters worse, Pip's whole demeanor has changed, which makes Joe feel even more out of place. The former apprentice blacksmith has been transformed into a young gentleman about town thanks to Abel Magwitch's generous bequest. He's a different man to the one Joe used to know.
Much of the humor of Pip's reunion with Joe comes from the blacksmith's complete lack of social graces. When Pip offers to take Joe's hat, Joe's reluctant to hand it over, holding it ever closer to him as if he were taking care of a precious bird's nest. Joe's trying so hard to act properly in polite society so as not to embarrass Pip, but he just makes himself look ridiculous. And he insists on calling Pip "sir," indicating that Joe's so overawed by Pip's new status as a gentleman of means that he's gone from being a bosom pal to little more than a servant.
When he's invited to sit down at the table, Joe finally lets go of his precious bird's nest of a hat. But as we might expect, all does not go according to plan. After Joe places his hat uncomfortably on the mantel-piece, it keeps falling off. Each time it does so, Joe picks it up, dusts it down and places it right back in the same place. After repeating the process several times, Joe ends up dropping the hat into the slop-basin, from where a highly embarrassed Pip retrieves it.
Even worse is to come when Joe sits down to lunch with Pip and Herbert. Joe's so self-conscious and nervous about breaching the rules of proper etiquette that he keeps accidentally dropping more food than he eats, all the while pretending that he hasn't dropped any. But Pip eventually realizes that Joe's awkward behavior is largely his fault. If he'd been more easy-going with Joe, then Joe would've felt more relaxed in his presence. As it was, though, Pip was too much of a snob, too quick to forget just how much Joe meant to him, that he treated him more as a country bumpkin than a dear old friend.