Prison Visitor (or Prison Cell) was a game played on the British edition of Whose Line.
A singing game much like Bartender or Psychiatrist, Prison Visitor saw one performer (almost invariably Josie Lawrence) taking the part of a Prison Visitor. The other performers would stand on the other side of a set of prison bars as the prisoners.
The crimes for which the prisoners were incarcerated were suggested by the audience.
Tony Slattery was particularly fond of subverting this game, on one occasion lifting the "bars" up and pretending to escape and on another swaying them in time to Josie's song.