I also have a Chewie that loves humping his favorite little stuffed animal. He's 5mo old and recently started doing it. It wasn't until a few days ago before his "lipstick" came out...LOL (that's so funny you call it that too). I have a feeling he just has to get excited to a certain point before it comes all the way out and trust me girl, when it comes out, you will be like, OMG! You'll definitely see it because it's not so small in relation to the size of the dog. So far, Chewie hasnt gone all the way and made a mess but I have a feeling it will happen soon once he finds his groove spot. Yesterday he started noticing what was going on down there so once the lipstick makes an apperance his head is between his legs for about 10min....LOL! I figure he's just discovering his little body and everything else will come in time. Good luck with your Chewy