zed@zed:~$ sudo sh -c "echo 'deb http://download.virtualbox.org/virtualbox/debian '$(lsb_release -cs)' contrib non-free' > /etc/apt/sources.list.d/virtualbox.list" && wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add - && sudo apt-get update && sudo apt-get install virtualbox-5.0
OK
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Hit:2 http://gb.archive.ubuntu.com/ubuntu xenial InRelease                     
Get:3 http://gb.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]
Get:4 http://download.virtualbox.org/virtualbox/debian xenial InRelease [7,894 B]
Get:5 http://gb.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]
Ign:4 http://download.virtualbox.org/virtualbox/debian xenial InRelease
Get:6 http://download.virtualbox.org/virtualbox/debian xenial/contrib amd64 Packages [1,469 B]
Get:7 http://download.virtualbox.org/virtualbox/debian xenial/contrib i386 Packages [1,478 B]
Fetched 317 kB in 3s (101 kB/s)     
Reading package lists... Done
W: GPG error: http://download.virtualbox.org/virtualbox/debian xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A2F683C52980AECF
W: The repository 'http://download.virtualbox.org/virtualbox/debian xenial InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libgsoap8 libvncserver1 linux-headers-4.4.0-31
  linux-headers-4.4.0-31-generic linux-image-4.4.0-31-generic
  linux-image-extra-4.4.0-31-generic virtualbox-dkms
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  libsdl-ttf2.0-0
The following packages will be REMOVED
  virtualbox virtualbox-guest-additions-iso virtualbox-qt
The following NEW packages will be installed
  libsdl-ttf2.0-0 virtualbox-5.0
0 to upgrade, 2 to newly install, 3 to remove and 0 not to upgrade.
Need to get 63.4 MB of archives.
After this operation, 14.2 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
WARNING: The following packages cannot be authenticated!
  virtualbox-5.0
Install these packages without verification? [y/N] y
Get:1 http://gb.archive.ubuntu.com/ubuntu xenial/universe amd64 libsdl-ttf2.0-0 amd64 2.0.11-3 [15.0 kB]
Get:2 http://download.virtualbox.org/virtualbox/debian xenial/contrib amd64 virtualbox-5.0 amd64 5.0.32-112930~Ubuntu~xenial [63.4 MB]
Fetched 63.4 MB in 15s (4,061 kB/s)                                            
Preconfiguring packages ...
(Reading database ... 245741 files and directories currently installed.)
Removing virtualbox-qt (5.0.32-dfsg-0ubuntu1.16.04.2) ...
Removing virtualbox-guest-additions-iso (5.0.32-0ubuntu1.16.04.2) ...
dpkg: virtualbox: dependency problems, but removing anyway as you requested:
 virtualbox-ext-pack depends on virtualbox (>= 5.0) | virtualbox-5.0 | virtualbox-5.1; however:
  Package virtualbox is to be removed.
  Package virtualbox-5.0 is not installed.
  Package virtualbox-5.1 is not installed.

Removing virtualbox (5.0.32-dfsg-0ubuntu1.16.04.2) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20160824-0ubuntu1) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ...
Processing triggers for desktop-file-utils (0.22-1ubuntu5) ...
Processing triggers for mime-support (3.59ubuntu1) ...
Processing triggers for shared-mime-info (1.5-2ubuntu0.1) ...
Processing triggers for hicolor-icon-theme (0.15-0ubuntu1) ...
Selecting previously unselected package virtualbox-5.0.
(Reading database ... 245440 files and directories currently installed.)
Preparing to unpack .../virtualbox-5.0_5.0.32-112930~Ubuntu~xenial_amd64.deb ...
dpkg: error processing archive /var/cache/apt/archives/virtualbox-5.0_5.0.32-112930~Ubuntu~xenial_amd64.deb (--unpack):
 subprocess new pre-installation script returned error exit status 1
Selecting previously unselected package libsdl-ttf2.0-0:amd64.
Preparing to unpack .../libsdl-ttf2.0-0_2.0.11-3_amd64.deb ...
Unpacking libsdl-ttf2.0-0:amd64 (2.0.11-3) ...
Errors were encountered while processing:
 /var/cache/apt/archives/virtualbox-5.0_5.0.32-112930~Ubuntu~xenial_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)