Green’s Dictionary of Slang

1. (US prison) dressed in one’s best clothes.

1967		M. Braly On the Yard (2002) 246: Cilly was able to see that he was bonerooed — pants glazed with starch and pressed to knife creases, and he had decorated his cap with a leather band, anchoring at the sides with white buttons.
1973		Maurer & Vogel Narcotics and Narcotic Addiction in Maurer Lang. Und. (1981) 284/2: bonaroo [...] 2. Wearing starched, pressed clothing in a prison or narcotics hospital.
2001		(con. 1975–6) E. Little Steel Toes 9: Red’s sloppy, doesn’t care if he’s bonarooed or not.

2. of a place, smartened up, embellished.

2001

(con. 1975–6) E. Little Steel Toes 113: This is one bad pad and one of the permanent variety, not just a bonarood hotel.