While not exactly notable for his sense of humour, Barty could still recognize and appreciate a joke, and he more than understood the other man's, which got a small, polite grin and an equally small, but genuine, laugh. More important than the joke, though, was the introduction and this other man's name. As he'd always been taught to do, Barty took and shook the other man's hand and his ears pricked up at the name: Aloysius Croaker.
So this was the one Barty was meant to be befriending. How fortuitous -- Barty had known that Croaker lived in Grindylow Gardens, but he had rather expected that finding the man would have taken more effort. Well, no matter. They had found each other, and now Barty just needed to play very nicely and get Croaker to continue trusting him.
"I'm Barty Crouch," he answered quickly, with a slight pause before he added on: "Junior, I mean. And I just moved in on Tuesday, sir, and Quality Quidditch Supplies keeps me rather preoccupied, for most of the day, so... I think you're only the second neighbor I've met, so far, actually." To prevent himself from rambling, Barty stopped there and gave Aloysius an awkward, but rather pleased, grin.