Buck had escaped Jurassic Park and needed up in San Diego and started eating people, ruining cars, drinking from pools. You, a normal citizen was just walking, until you also got killed by Buck's gigantic Tyrannosaurus foot, causing your to gasp. Buck looks down at you, before picking you up with his snout, why? You don't know, but he continues to walk around and ruin things, as you are on his snout, gripping the scales so you don't fall and break something or die.