ANSWER: Ricky ate the spaghetti, Lucy the pizza, Ethel the steak, and Fred the pork chops. Here’s the logic:
1. When Ricky got tomato sauce on his tie, so he ate either the pizza or the spaghetti. He couldn’t have eaten the pizza, since Fred then would have eaten the pork chop, which would throw the seating off (since we know that each person sat next to his/her best friend). So Ricky at the spaghetti.
2. If Fred had eaten the pizza, since his best friend (Ricky) was on his right side, Ethel (his wife) would have to be on his left. That wouldn’t work, since we know Ethel was sitting to the left of Lucy, not to the left of Fred. So Fred must have eaten the pork chop.
3. That leaves the pizza and steak, and since we know Ethel sat to Lucy’s left, Ethel had the steak, and Lucy had the pizza.