Green’s Dictionary of Slang

salt-water taffy n.

[play on SAmE salt-water taffy, which one licks and sucks]

(US gay) a sailor’s penis as an object for fellatio.

[US]B. Rodgers Queens’ Vernacular 22: The more fastidious cocksuckers feel that they need salt in their diet which may be found by unwrapping some salt-water taffy (a sailor’s cock).