Humping
Another behavior that is often seen in puppies and even adult dogs that is viewed as inappropriate behavior is mounting. In actuality, mounting another dog in mock mating (or in actual mating) is quite normal for dogs. Puppies of both sexes will practice this maneuver as a part of their play and aren't picky as to which sex the recipient is. Usually, mounting behavior fades as the puppy reaches maturity and is altered. Sometimes, however, a puppy will mount a child, a pillow, or your leg, causing a very embarrassing situation for the owner. In these cases, it may not be possible to ignore the behavior and hope it fades over time. If immediate action is necessary, there are several ways you can proceed.
If the puppy has chosen an object to mount, such as a couch pillow, simply take the pillow and put it in a place where the puppy can't get to it. If a puppy is using a person as her practice object, say “Aaah!” loudly to distract her, which should stop her humping momentarily. Then, give her a command that she knows how to do (such as sit) and reward her for the sit.
What you don't want to do when trying to discourage a behavior, such as mounting, is to yell or holler at your dog. Though it would seem that harsh verbal corrections would lessen the dog's desire to perform the behavior, precisely the opposite is true. With dogs, any attention — whether good or bad — can be rewarding. If a dog finds she is rewarded for a behavior, this will reinforce the behavior, making it that much harder for you to extinguish later.

