My other dog does not have this problem. When this first happened, I left it alone and hoped it would go back in on it's own, but in the morning it was still out. I had to manually pull his skin down and back up. It appears the skin gets tucked in. This happens almost everytime he "plays" with his toy rabbit. How do I get it to go in by itself? Does anyone else have this problem?
He is neutered, I had him neutered at 5 months, he's now 1.5 years old. I don't discourage him from "playing" with rabbit, because it keeps him from doing that to people's leg. So I'm ok if he wants to go at it with the stuff rabbit, as long as that's the only thing he's doing it with.
So if he's neutered, he shouldn't be doing that at all? Because my other dog does it too and he was neutered at 4 months, but he's lipstick goes in on it's own.

If by "play" you mean hump - and by "lipstick" you mean his penis -- take the rabbit away. Your dog has a problem with his penis that needs to be taken care of by a vet and you are only encouraging his behavior (which can lead to infection, sores, dry skin, etc).

Get him neutered!

what does "plays" and "lipstick" stand for... i dont get it

That the rabbit away from him! he is getting to aroused by playing with it!

Also this is a very serious problem for him to have it keep happeneing. If his penis get very dried out then it can become cracked and infected! You should mention this to your vet too because for some reason he is not making enough sheath lubrication to have his penis go back into it!

Geeze!

Need a lot more information.

How old is your malti-pom?

Is your Malti-pom neutered?

I'm assuming "plays" means humping. If he is not neutered it could be a sign of sexual maturity.

Humping is reduced by neutering, as is the risk of testicular cancer.

If he is netuered, it could be a display of dominance.

Sometimes when male dogs get excited, are extremely playful or in a hyper mood... that can happen with the "lipstick" as you call it, sticking out.

if he is not neutered please consider doing so asap. If he is neutered, you may want to replace the toy rabbit with something else. The rabbit may look too realistic.

Get him neutered and hopefully he'll stop humping his cuddly toy. In the meantime - throw the rabbit away and don't encourage him to love up anything else. Sounds like he has a problem with his foreskin which you might want to speak to the vet about - do him a favour and book him in to be castrated at the same time.