hacked with cialis and levitra messages

Hello Support,
Is anyone familiar with this hack - when you do a google search of our website, it comes back with cialis/levitra/etc. messages on google. You don't actually see these messages on the website. They show up on google.
Here's how to get it: go on google, and do a search for Mariposa Habitat for Humanity. The website is mariposahabitat.org.
Anyone got any suggestions on how to take all of this out?
Thanks,
Carol