In this passage, Daisy describes herself as "sophisticated." However, when doing so, she also laughs with scorn, suggesting that she is speaking ironically.
The main implication in the passage is that Daisy is aware of the fact that others consider her "sophisticated." However, it seems like she does not believe she fits this epithet. A person who is sophisticated is one who is knowledgeable about the world, is up-to-date with cultural trends and has had a variety of experiences. This is also linked, to some extent, to people who are relatively wealthy. By showing disdain for the idea, Daisy is showing that she does not believe that most people who claim to be sophisticated (such as the upper class people who surround her) are actually sophisticated, and that she is above them because she realizes she cannot truly claim to be so.
