hard-rock hotel, n. — Green’s Dictionary of Slang

hard-rock hotel n.

also hard-rock cafe, ...city

[the stones from which it is built + ? the rocks that prisoners are made to break + (in case of cafe) the international chain of rock ’n’ roll themed restaurants ]

(US) a prison.

1939		W. Guthrie in Lomax Folk Songs of North America (1960) 428: If all the jails I been in was all put together, it would make a hard rock hotel as big as the Capitol building.
1970		E. Thompson Garden of Sand (1981) 419: Catch us with that stuff and it’s hard-rock city.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 84/2: hard rock cafe n. a prison.