Here's the gist: Bart sees a quarter and attempts to pick it up, but it's glued to the sidewalk. The Riverdale Gang is gloating over their successful prank...
... until they remember their deceased buddy, Archie. Archie would have loved this prank...
They then drive back to Riverdale with a photographic memoir of their good friend back when he was still with them.
And this is why you shouldn't miss "The Simpsons."