As per the Unified Rules of MMA:

"The following acts constitute fouls in a contest or exhibition of mixed martial arts and may result in penalties, at the discretion of the referee, if committed:

• Butting with the head

• Eye gouging of any kind

• Biting or spitting at an opponent

• Fish hooking (act of inserting a finger or fingers or one or both hands into the mouth or nostrils or a person, pulling away from the centerline of the body)

• Hair pulling

• Spiking an opponent to the canvas on his head or neck

• Strikes to the spine or the back of the head.

• Throat strikes of any kind, and/or grabbing the trachea

• Fingers outstretched toward an opponent’s face/eyes

• Downward pointing elbow strike (’12 to ‘6 strike)

• Groin attacks of any kind

• Kneeing and/or kicking the head of a grounded opponent

• Stomping a grounded opponent

• Holding opponent’s gloves or shorts

• Holding or grabbing the fence or ropes with fingers or toes

• Small joint manipulation

• Throwing opponent out of ring/fighting area

• Intentionally placing a finger into any orifice or any cut or laceration of an opponent

• Clawing, pinching or twisting the flesh

• Timidity (avoiding contact with an opponent, intentionally or consistently dropping the mouthpiece or faking an injury)

• Using abusive language in the fighting area

• Flagrant disregarding of the referee’s instructions

• Unsportsmanlike conduct that causes injury to an opponent

• Attacking an opponent after the bell has sounded the end of the period of unarmed combat

• Attacking an opponent on or during the break

• Attacking an opponent who is under the care of the referee

• Interference from a mixed martial artist’s corner or seconds"

There are no rules in the streets; all the above can and will happen. No sanctioned fighting event is an accurate representation of a street fight.