The script asks for confirmation before allowing someone to enter your page
How To Add Confirmation box to Blogger
1.Login to your blogger dashboard and go to Desing --& Page Elements.
2.Click on 'Add a Gadget' on the sidebar.
<script> if (!confirm("Do you want to enter this site?")) window.location=history.back() </script>
Note: Change pop up text Do you want to enter this site? as you like.
Now You are done