To do this you can start a new blog, give it a name, and make sure it won't show up in your profile:
Go to your profile page (by clicking on your avatar)
Click on Edit Profile
Click on Select blogs to display
Make sure your test blog is not marked
To avoid the blog showing up in Google search results go to the dashboard of your test blog and go to Settings. Here you can edit the privacy settings.
next episode: Monsieur Schmit