This exercise is similar to ankle bounces (as the title implies), but instead of standing up straight you’ll be leaning over on an object. Bent over donkey ankle bounces just give you another angle to attack your calf muscles from. Also, if your knees bother you for some reason this exercise may be easier than regular ankle bounces.
To begin, find an object that is about waist high. Make sure the object is steady or else you could fall and break/pull something. Something like a kitchen counter would work pretty well. Once you’ve got your support object all set up, lean over until your back is about parallel with the ground (basically like your leaning over to rest on the object). The majority of your upper body weight should be resting on the object. Your legs should be able to stay straight as you do this.
Once you’re in this position, begin to bounce using only your calves to propel you off the floor. Start with low bent over ankle bounces first until you get a feel for them. Sometimes it can be a little disorienting at first. Once you get the hang of it, start bouncing higher. Remember that if bent over ankle bounces get too easy with two legs, you can do them with one leg.