With the oxford comma, the sentence implies that the individual had eggs, toast, and orange juice separately. Without it, the sentence implies that the individual had eggs and toast with orange juice on it.
This cartoon shows that with the oxford comma, the sentence shows that we invited 3 different groups of individuals: the strippers, JFK, and Stalin. Without the oxford comma, the sentence implies that only 2 individuals were invited, and those are the 2 strippers, JFK and Stalin. Without the comma, the sentence is interpreted incorrectly, and comically.