A motorcycle racer is knocked out and left on an isolated dirt road in the Sonoran Desert near Tucson by some bikers who steal his brand new motorcycle. When he regains consciousness he sees a gila monster on the road. He looks at it, then walks away from it because he's a native and knows that they're harmless. Later he is trying to scare a biker chick to stay with him so he tells her that the desert is full of killer rattlesnakes and gila monsters. She falls for it.
They used a nice live healthy-looking Reticulate Gila Monster for the role.