radio, n. — Green’s Dictionary of Slang

radio n.

[? pun]

a toasted tuna fish sandwich on white bread.

1966

in Newark (OH) Advocate 21 May 3/3–4: radio -- tuna fish sandwich on toasted white bread.

SE in slang uses

In compounds

radio windy (n.)

(N.Z. prison) an overly talkative inmate [Radio Windy, a 1970s prirate radio station at Wellington].

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 151/1: Radio Windy n. a talkative, indiscreet inmate, who gives away the good ideas and secret plans of his fellow inmates .

In phrases

put something on the radio (v.) [i.e. to ‘broadcast’]

to publicize something.

1968

N. Heard Howard Street 109: I didn’t mean for that loudmouth to put it on the radio.