To give you an example, there was a reorg a few years ago to outsource NSA's IT. (Makes a lot of sense that an agency that pretty much only does IT would outsource IT, right?)
In the reorg, 500+ people were identified as having no discernible skill that was relevant to the mission. They were segregated into their own org and given busy work. When the outsourcing occurred, the contractor was incentivized to employ and retain them for 2 years, including the 500+. To entice them, they paid them above their government salary.
The contractor could not figure out what to do with them either. It treated them as "casual employees". They were given a salary, but did not have to report to work and had no responsibilities. For 2 years.
Once the incentive ran out, these folks went back to NSA and got rehired as government employees. According to the hiring rules, they went right to the top of the stack.