For a standard user your code will remove access item 84 (Hard coded????)
You're calling SPListItem.BreakRoleInheritance with the parameter false, which means break role inheritance without copying any permissions. The result of this will be that nobody has access to the item. Except for site collection admins (and persons granted access at web app level).
Usually you'll follow the call to BreakRoleInheritance with adding some permissions. See How to: Break Role Assignment Inheritance
Your code is similar to an priviledged user doing the following in the UI:
- Go to the list.
- Select Item 84.
- Click Item permissions.
- Click Stop Inheriting Permissions.
- Select all users/groups.
- Click Remove User Permissions
In the comment you state that users should only be allowed to see Items they've created themselves. If that's your requirement then you don't need an event receiver. Instead do the following:
- Go to the list
- In the ribbon select List Settings
- Click Advanced Settings
- Set Item-level permissions like this:
- Click OK
The same can be achived programatically by setting SPList.ReadSecurity and SPList.WriteSecurity
If this isn't enough and you need specific rights to each item then read How to: Work with Roles and How to: Break Role Assignment Inheritance