Milly and the teddy

I noticed a few days ago that when milly was playing with her favourite teddy.That she kept trying to hump it is This normal behaviour for a bitch.When i told my oh what i had seen her doing he just said she is confused at the Moment.What he means by that i havent a clue

Sophie does that on occasions with her boomer ball it looks so funny.

Cairo had a huge teddy that she tried humping sometimes.Its their way of showing the toy whos boss

Moo's not done it but a friends female bitch would try a mate with Moo's head! Had me in stitches

my mom told me few days ago that their yorkshire terrier is doing that to her teddy as well! I was laughing when I heard about it but my sister is disgusted
my parents got another (younger) female dog and a female cat, and the terrier feels like a leader I think (which is hilarious because the dog is a great dane so it's 20 times bigger, and the cat is big and fluffy persian ). she's even peeing with her paw lifted sometimes, just like male dogs.

I agree with Lisa that she's probably showing who's the boss here

This is a very dominant behaviour, mounting in females/cocking its leg wow stepping over another dog and taking its time doing it, lying on another dog, is dominant behaviour, you should try to nip it in bud it can turn into a number of problems in the future such aggression if said toy was to be touched or taken away and if they do it to another dog that other dogs may not like it and you can have a very serious problem on your hands.
sure enough as a pup she is confused and its all probabily play right now but once she reach sexual maturity and still does its time for a few changes.