“Popping a cell” (Rikers slang)

New York magazine published a cover story about the Rikers Island correctional facility on June 28, 2015. A recent inmate explained what “popping” a cell means:
 
“I learned how to get out of my cell without the guard opening the gate. They call it ‘popping the cell.’ Once the guard opens your cell, all you gotta do is stick some tissue in the mechanism. It reads on their board as closed, but you can shake it and open it up on your own from that moment on.”
 
   
Wikipedia: Rikers Island
Rikers Island (/ˈraɪkərz/) is New York City’s main jail complex, as well as the name of the 413.17-acre (1.672 km2) island on which it sits, in the East River between Queens and the mainland Bronx, adjacent to the runways of LaGuardia Airport. Supposedly named after Abraham Rycken, the island is home to one of the world’s largest correctional institutions. The island itself is part of the Bronx, though it is included as part of Queens Community Board 1 and has a Queens ZIP code of 11370. The jail complex, operated by the New York City Department of Correction, has a budget of $860 million a year, a staff of 9,000 officers and 1,500 civilians managing 100,000 admissions per year and an average daily population of 14,000 inmates. However, it is notorious for abuse and neglect of prisoners in recent years, which has attracted increased media and judicial scrutiny that resulted in numerous rulings against the New York City government. In May 2013, Rikers Island ranked as one of the ten worst prisons in the United States, based on reporting in Mother Jones magazine.
 
New York magazine
Inside Rikers Island
June 28, 2015
9:00 p.m.
(...)
“Boofing” a Weapon and “Popping” a Cell
“You need your weapon. You need to learn how to keep that weapon from getting found. There’s a technique called ‘boofing.’ You take a weapon and you wrap it up and it goes into your rectum. I learned how to get out of my cell without the guard opening the gate. They call it ‘popping the cell.’ Once the guard opens your cell, all you gotta do is stick some tissue in the mechanism. It reads on their board as closed, but you can shake it and open it up on your own from that moment on.”
ROBERT EADDY, RECENT INMATE