apt-get install thing
Reading package lists... Done
Building dependency tree       
Reading state information... Done
thing is already the newest version.
The following packages were automatically installed and are no longer required:
  linux-image-3.2.0-116-generic linux-image-3.2.0-111-generic
  linux-image-3.2.0-109-generic linux-image-3.2.0-107-generic
  linux-image-3.2.0-110-generic linux-image-3.2.0-105-generic
  linux-image-3.2.0-113-generic
Use 'apt-get autoremove' to remove them.