[ziber@bravo] (~) $ sudo deluser whoopsie
Removing user `whoopsie' ...
Warning: group `whoopsie' has no more members.
userdel: user whoopsie is currently logged in
/usr/sbin/deluser: `/usr/sbin/userdel whoopsie' returned error code 8. Exiting.
[ziber@bravo] (~) $ who
ziber    pts/2        2013-02-12 14:10
ziber    pts/0        2013-01-10 22:36
ziber    pts/3        2013-02-12 14:18
ziber    pts/4        2013-02-12 14:21