Doing time' is a phrase used to describe the experience of being incarcerated in a prison or jail. It is often used to refer to the period of time that an individual is sentenced to serve in a correctional facility. The two crossword solutions for this phrase are 'INSIDE' and 'instir, ' both of which are six letters long. 'INSIDE' refers to the physical location of the prison, while 'instir' is a slang term for imprisonment.