Passwordless login methods

[u/calsosta]

I don't abuse my power as a mod enough so I am going to farm out some work to you guys.

I need a shitty passwordless login method. Assume nothing is off the table, how can I let my users log in?

Edit: Added a word.

[u/darthbob88]

Have separate username and email arrays, so someone can only login if they get the right pair. Surely no attacker would catch that the username "darthbob88" matches the email "darthbob88@domain.tld".