Astonishing Facebook notifications?

[Louise]

I think your friends suggested you to other friends. We can suggest a friend to someone. Following are the steps.

Click the gear button(*) at the top of your friend's profile (timeline), then click the Suggest Friends link.
Select the friend(s) you want to suggest. To find a particular friend, you can type their name in the Find Friends field or scroll through your complete Friends List. You can click the Filter Friends drop-down to sort your friends by network or Friend List.
Once you make all of your selections, click the Send Suggestions button. Each friend that you selected will receive an invitation to add your friend as a friend.

If u have doubt that your account was hacked, then using Facebook security features try to secure it more. Change your password too..