Green’s Dictionary of Slang

(US prison) ice-cream and other sweets purchased from the prison canteen.

1971–2		C. Shafer ‘Catheads [...] and Cho-Cho Sticks’ in Abernethy Bounty of Texas (1990) 201: cho-choes, n. – candies and snacks purchased from a prison commissary. [...] cho-cho book, n. – convicts’ commissary or script book. [...] cho-cho sticks, n. – ice-cream bars on sticks.
2000		Other Side of the Wall: Prisoner’s Dict. July 🌐 Cho-Cho: An ice cream bar bought in the canteen (TX).
2006		Prison Slang Mommyblogger mydogharriet.blogspot.com 26 Sept. 🌐 If she calms down, you can let her walk down her paper with some cho cho in front of Sesame Street.