That shopkeeper seriously took it over the top, Pretending to be a "Jim Roberts" is hardly an offense. Anyway those insults and swearing by the shopkeeper were really uncalled for and is not a good way to deal with prank calls.
Was funny though but when there's excessive swearing then It just gets bad.
Biznatch if you want to hear some good prank calls then hear some prank calls from a guy called VILLEST on youtube. They don't contain any swearing but are creative in the sense of fooling the person being called, which adds to the humour.