Below, I would like to create the following effect on a button element in CSS:

Whereas I just want a basic regular button but with the 'tab' sticking out of the bottom.
How do I do this?
I've tried ::after and ::before, but neither even show any results for some reason (and I don't really know how to use those rules either).
.button { background: #aaa; font-size: 16px; color: #000; padding: 8px; width: 200px; border: 3px solid #000; border-radius: 6px; } .button::after { width: 10px; height: 100px; background: #aaa; } <button class="button">BUTTON</button>
content: ''to your pseudo-element, otherwise it wont appear.