Green’s Dictionary of Slang

tick-tock n.

[its regular beating]

1. (US black, also tick) the heart, the heartbeat.

[US]D. Burley N.Y. Amsterdam News 7 June. 13: Them pistols [...] gonna have tops that’ll cut my tick-tock right across the middle.
[US]D. Burley Orig. Hbk of Harlem Jive 21: My own tick-tock to thee I bare.
[US]Big L ‘Ebonics’ 🎵 A sweat box is a small club, your tick is your heart.

2. (Aus. Und./US, also box of tick-tocks) a clock or watch.

[US]Ekalaka Eagle (MT) 25 July 2/2: ‘Where’s the tick-tock?’ he asked [...] — The clock!’ cried old ‘Kiowa’ loudly [...] ‘Why?’.
[US]D. Burley N.Y. Amsterdam News 7 Apr. 14: The chiming box of tock-tocks with the double-sided face.
[Aus]‘No. 35’ Argot in G. Simes DAUS (1993).
[[Aus]S. Maloney Sucked In 231: They showed him the photo of a watch [...] Quite a flashy piece of tock-tockery, apparently].