What does it mean if someone says they need a "T"?

Theres a guy in my neighborhood who isnt the best of dudes. He's really mean and stuff and is a horrible person. He is a grown man and recently I heard him talking on a phone at a convenient store and he said he needed a "t". I have no idea what that means and I would really like to know. Does it mean drugs? Or something else? I really nee d help so someone please answer!!