What three habits of gatsbys Speaking make nick believe he was lying about his past

From the text;

"He looked at me sideways — and I knew why Jordan Baker had believed he was lying. He hurried the phrase “educated at Oxford,” or swallowed it, or choked on it, as though it had bothered him before. And with this doubt, his whole statement fell to pieces, and I wondered if there wasn’t something a little sinister about him, after all."

"His voice was solemn, as if the memory of that sudden extinction of a clan still haunted him. For a moment I suspected that he was pulling my leg, but a glance at him convinced me otherwise."

"I managed to restrain my incredulous laughter. The very phrases were worn so threadbare that they evoked no image except that of a turbaned “character” leaking sawdust at every pore as he pursued a tiger through the Bois de Boulogne."

Thus, we have sideways glances, inappropriate smiles, a solemn voice, and threadbare, over used phrases.