Florida, n. — Green’s Dictionary of Slang

Florida n.

[the siting of such cells in the warmest areas of the prison, often underground]

(US prison) the solitary confinement/punishment block.

1960		E. De Roo Big Rumble 96: Man, you been to Florida? [...] You took a trip to the moon maybe?
1983		R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].