King of Snake (1987)

A research lab has developed "The Formula", a box that allows living organic material to grow hundreds of times its original size. Criminals invade the lab to steal it, but it's thrown off the side of the road. There it's found by a girl who decides it will be the perfect home for Mosler, the snake she has adopted. Mosler immediately outgrows the box, springing to the ground like a pile of novelty dog poo. Gang members see the girl and her huge snake frolicking outside and put two and two together. Mosler thwarts their first attempt to snatch her, but when they do succeed he goes on a rampage trying to find his friend