A cell search, also known as shakedown, is something that the guards will choose 2 inmates, then they will check their cells for anything that will be confiscated or is a weapon.
They also cover up holes in the wall and floor, even if you were planning to escape or get to the prison stash. If you have anything that's left uncovered like a vent or a hole or if you have contraband in your chest, they will take it away, cover up the holes, and put you in a solitary.
One way they announce a shakedown is, "The following morons have won a cell search:" then they will say who. They announce it in the morning roll call, and evening roll call, but sometimes there is also an afternoon roll call.