If you don't want him exhibiting this behaviour in the future. 1st and foremost don't laugh at him even though I know it's cute. Then pick him up off his little friend and say no. This is what I did with Logan and it's seemed to work. sometimes I'll catch him doing it after we've went to bed or in private. It is not a sexual thing at this age it is a dominance thing. Also once you stop him from humping his little friend getting him occupied doing something else.
__________________  Ponyup Mom to LOGAN  |