While having a sandwich, Gould customarily empties a bottle or two of ketchup on his plate and eats it with a spoon.
Americans in general like ketchup, though obviously not always to this extent of dumping out an entire bottle. Got a steak that doesn't taste too good? put some ketchup on it. Got some fries that aren't salty? put some ketchup on it. Your only main source of food is a chair cushion? Put some ketchup on it. It'll taste good!
However, in this case, most Americans don't put so much ketchup out. It's disgusting, and even Gould admits it. In the end, he really just wants the free shit, and the restaurants aren't exactly happy in regards to that.