In the world of account trading, "unchecked" lists are typically databases of usernames and passwords (often called "combolists") leaked from other websites.
Have a friend gift you items through the official in-game Item Shop. Sources: Epic Games Terms of Service FBI - Cyber Crime Information Fortnite Community Guidelines Malwarebytes - Gaming Account Theft Epic Games Account Security Guide Fortnite Competitive Rules - Account Sharing Department of Justice - Computer Crime Laws Download 500 Fortnite accounts UNCHECKED NICE HITS txt
Users run these lists through automated "checkers" to see if the same credentials work on Fortnite [2]. In the world of account trading, "unchecked" lists
Accessing an account without permission is a violation of the Computer Fraud and Abuse Act (in the US) and similar laws elsewhere [7]. How to Safely Get a Fortnite Account Accessing an account without permission is a violation
Even if a "hit" works, the original owner can usually recover it via Epic Games Support. This means any time or money you invest in the account will be lost when the real owner resets the password [5].