get up on its hind legs
Of a four-legged animal, to stand on its back legs. If you're trying to teach the dog to get up on its hind legs, why don't you use treats as an incentive?
get up on one's hind legs
Fig. to get angry and assertive. (Alludes to the action of a horse when it is excited or frightened.) She got up on her hind legs and told them all to go to blazes. She has a tendency to get up on her hind legs and tell people off.