function for colliding without using rigid body's?

function OnCollisionEnter (collision : Collision)
{

if(CrateMission.CrateMission == true)
{

if(collision.gameObject.tag == "Player" && !isHit)
      {

           isHit = true;
           animation.Play("crate");
           PlayerStats.CRATES +=1 ;

           Destroy(gameObject,KillTime);
     }

 }
}

here is my script however i believe i have to add a rigid body to both of the objects i have a charter with a mesh collider convex and i want him to collide with the crate then the function happens what is the best function to use i dont want to attach a rigid body to my worm but don't mind if it is attached to the crate

please help thanx :)

Add a collider to the box. It's not the same as the rigidbody, and will allow your character to collide with it, triggering the collision function and the rest of your code.