[djur]

Whenever I implement a bulk delete feature I tell the user how many records they're about to delete and ask them to type it back in.

If it's possible they're trying to delete data from the wrong place (say, an administrative account that manages many customers) another safeguard is to have them select the name of the context (customer name, etc.) out of a list of four or five nonsense alternatives.

The user experience tends to involve a lot of double takes and rereading, which is precisely what I want.

[alxndr]

In another comment, derefr points out that GitHub similarly makes you type the name of the repo when you delete it.