"I like pies" is a short phrase used to change the current topic of conversation, or perhaps fill a mental void with an inviting picture of food. It is important to respond to such a statement with something that wasn't being talked about before, unless, of course, pies were actually the topic of conversation. In this case it is safe to assume that the comment actually meant something.

Often people mistakenly utter something about the state of the weather -- shame about all this rain -- when they really ought to have stated that they like pies. It's quite likely that Freud has something to say about this, but no one trusts him anyhow, so it doesn't really matter.