Really! I thought everyone could see them. Let me figure it out and I'll get back.
Note: I am having trouble recreating it again. It was happening to me a lot last night when I was posting comments. I can remember being annoyed because I had to stare at this big belly while I was typing.
I am going to keep watching for it and if I can pinpoint it I'll let you know. (I did post a comment about the bellies being back in the BV chat thread and another member commented she had seen them too.)
Anytime you are seeing banners or anything that the Management doesn't know about, it might be a good idea to go to malwarebytes.org, download the free version, and run a complete system scan.
Or if there is a nearby nerd you can seize, consider having her take a look at your overall security and browser situation, and maybe update and upgrade some things.
It is extremely easy to "get stuff" on your computer these days unless you take very aggressive pro-active steps to prevent it, and keep it up on a consistent basis - because that's what the people who want you to get those belly fat banners are doing!
Just to give you an idea, the malwarebytes database sometimes updates four or five times a day!
There are that many people out there who want to put stuff on your computer!