protected void CheckCollisions()
        {

            //Loop through each collision group (CG1)
            foreach (KeyValuePair<string, CollisionGroup> CG in CollisionGroups)
            {

                //Only process collision groups that both have objects and have something to collide with.
                if (CG.Value.Collidables.Count > 0 && CG.Value.CollidesWith.Count > 0)
                {

                    //Loop through each collision group (CG2) that this group (CG1) can collide with
                    foreach (string Key in CG.Value.CollidesWith)
                    {

                        //Does CG2 even exist?
                        if (CollisionGroups.ContainsKey(Key))
                        {

                            //Only process if that collision group contains something to collide with
                            if (CollisionGroups[Key].Collidables.Count > 0)
                            {

                                //Compare every object from CG1 against CG2
                                foreach (Collidable C1 in CG.Value.Collidables)
                                {//CG1 Tier

                                    foreach (Collidable C2 in CollisionGroups[Key].Collidables)
                                    {//CG2 Tier

                                        //Check if they collide with each other
                                        if (MathUtil.RectIntersect(C1.GetBounds(), C2.GetBounds()))
                                        {

                                            //Trigger the collision
                                            C1.Collision(C2);
                                            C2.Collision(C1);

                                        }

                                    }

                                }

                            }

                        }

                    }

                }

            }

        }