Baby Bear's lunch is interrupted.
Backstory: Apparently the Three Bears from the story moved to Sesame Street sometime in the early '90s and have been regular characters on the show ever since.
One day, circa 2007, I was at my sister's house watching Sesame Street with her and my nephew (and if I'm right about the year, he would have been my only nephew at that time), and realizing that I hadn't watched Sesame Street in a looooooong time because I didn't recognize about half the characters. Anyway, there was a bit with Baby Bear, and my sister said something to the effect of "Ugh, I can't STAND Baby Bear!" And while I don't see eye-to-eye with my sister on everything, I completely agree with her on that point. Generally speaking, Baby Bear is REALLY annoying. Particularly his speech impediment; it's not consistent, which leads me to believe it's just an affectation.
So one may say that what Ernie does here with Goldie-Duckie is a mean thing to do, and while I don't disagree, I find that I don't really mind, either. Also, BB himself points out that Goldie-Duckie is just a toy and therefore not really eating his porridge. So what are you complaining about?
And for periperal annoyance factor, ever since the Bear family moved to Sesame Street, apparently everybody had to start referring to oatmeal as "porridge" in every sketch, regardless of whether or not it actually involved one of the Bears.
But in fairness, Baby Bear does have his moments, like the Street story about his doll--which, if you have 15 minutes to spare, you can watch here. It was awesome for so many reasons, among them the fact that it was sophisticated storytelling that made use of irony...and because Gordon looks FANTASTIC in a pink shirt!