Way of the Street Fighter

You're not like other monks, you weren't trained or raised on a misty mountain top with all the time in the world to hone your body and skills - the world was your gym and the street your trainer. 

Street Smarts

The street was your monastery, your home, and your master. When you take this subclass as 3rd level, you add your Proficiency bonus to your initiative modifier.  Additionally, you know Thieves' Cant.

Street Fighting

At 3rd level, you gain proficiency with improvised weapons, and these weapons do your martial arts die one step up for damage. So if your martial arts die is a 1d4, they would do a 1d6, and so on. Improvised Weapons are treated as monk weapons for you, and as such, you can use your Dexterity to make attacks with them. Additionally, due to your extensive experience grappling, shoving, and generally using your body in a fight, you gain a bonus to your Athletics modifier equal to your Wisdom Modifier.

One to the Chin

By 6th level, you know how to take a beating better than any other monk and can get back up no matter how hard the blow. You gain two extra hit points per monk level. 

Additionally, if a creature ever causes you to be knocked prone, you can use your reaction to stand back up.

Sixth Sense

At 11th level, if you spend at least one minute interacting with or studying a creature, you can tell if the creature is armed, what their alignment is, and how much gold they are carrying. Additionally, as an action, you can make an insight check (DC 10 + the target's Deception modifier) to gain advantage on your first weapon attack against a target and give them disadvantage on their next weapon attack on you.

Kick ‘em While They’re Down

At 17th level, if a creature within 5ft of you falls prone, you can use your reaction to make an unarmed attack against that creature. Additionally, if you have advantage on an attack, you can add your Wisdom Modifier to the attack and damage rolls.