Green’s Dictionary of Slang

tin and tap n.

also tip and tap

[rhy. sl.]

(US Und.) a cap.

1935		A.J. Pollock Und. Speaks n.p.: Tip and tap, a cap.
1944		Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3.
1953		Berrey & Van den Bark Amer. Thes. Sl. (2nd edn).