ちんちん (bell ringing sound)

The sound of a small bell ringing or a kettle whistling — ching-ching or ding-ding. Used for the streetcar/tram bell, bicycle bells, and other small metallic rings. ちんちん電車 = 'ding-ding train,' the affectionate colloquial name for a tram/streetcar. Sometimes written in katakana (チンチン) for emphasis.