I went for an extraction. the first needle i got shocks down my tongue which i never had after second needle in seconds i passed out?

Not common: When the dentist injects local anesthetic the goal is to place it next to the nerve. The solution soaks in and you get numb. We are however aiming for something we can not see. Sometimes the needle actually touches the nerve. This causes the shocks down your tongue that you felt. Usually just a temporary, although uncomfortable, feeling. You probably fainted from the second shot due to anxiety.

Lingual nerve: The first injection hit the lingual nerve which caused the tongue to feel a shock -is normal in some cases with tongue becoming numb immediately you passed out from fright- fear or a vagal- vagal response -lack of oxygen.

Dental injection: You likely passed out due to anxiety or psychogenic shock. The tingle or shock in the tongue you felt is related to the anesthesia or needle being close to the nerve when the anesthesia was administered. While this doesn't happen every time with a lower injection, it happens quite often and is usually scary for the patient that has not experienced it but is insignificant other than that.