# skipping ask password for users with sudo
<USER_NAME>	ALL=(ALL:ALL) NOPASSWD: ALL

You can configure sudo to never ask for your password.
Open a Terminal window and type:
sudo visudo
In the bottom of the file, add the following line:
$USER ALL=(ALL) NOPASSWD: ALL
Where $USER is your username on your system. Save and close the sudoers file (if you haven't changed your default terminal editor (you'll know if you have), press Ctl + x to exit nano and it'll prompt you to save).
As of Ubuntu 19.04, the file should now look something like
#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults env_reset
Defaults mail_badpass
Defaults secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin"
# Host alias specification
# User alias specification
# Cmnd alias specification
# User privilege specification
root ALL=(ALL:ALL) ALL
# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL
# Allow members of group sudo to execute any command
%sudo ALL=(ALL:ALL) ALL
# See sudoers(5) for more information on "#include" directives:
#includedir /etc/sudoers.d
YOUR_USERNAME_HERE ALL=(ALL) NOPASSWD: ALL

# Run `visudo` to edit the file `/etc/sudoers`:
sudo visudo
# For example, to allow the `shutdown` command to run without a password.
# Add this to the file, replacing `myusername` with your own login name for your PC:
myusername ALL = NOPASSWD: /sbin/shutdown
# NOTE: `sudo` is still required to run the command so you still have to specify the command as:
sudo shutdown

# Run the following command
sudo visudo
# Add the following to the bottom of the file and substitute 'username'
# for your own linux username
username ALL=(ALL) NOPASSWD:ALL