"Titters" Natural Recordings by Native Speakers
To laugh or stifle a laugh, especially in a quiet or restrained manner; to make a low, stifled, or nervous laugh: "She tried not to titter to herself as she heard the silly joke."
A colloquial or informal term for a woman's breast. It's often used in casual settings, but its connotation can be considered somewhat playful or affectionate rather than slang in some cultures.