When kangaroos become aggressive, their behavior can be surprisingly intense and highly physical, driven mostly by territorial instincts, competition for mates, or feeling threatened. A male kangaroo, especially a large one, may square up on its hind legs, puff out its chest, and stare down an opponent before engaging. If the threat persists, the kangaroo may lash out with powerful forearm jabs, grab and grapple much like a boxer, or deliver explosive kicks using its muscular hind legs while bal