For example, the sentence "Todd liked crunchy apples, brown bananas, and small oranges" sounds better than "Todd liked crunchy apples and brown bananas".
Generally, if you're listing off things, three items (at least when compared with only two items) sounds "correct" or "more complete" in a sort of rhythmic or aesthetic sense. What might be a reason for this? Is it specific to English? As a native English speaker it seems almost like an unwritten rule of the language.
This question was inspired by a bit from the sitcom 30 Rock.
