Trying to find a Billy and Mandy episode

Hey there everyone. I was watching some episodes of Billy and Mandy with my friend today when I was reminded of a scene from an episode that I haven't seen in years. Curious about what episode would include the scene, I looked it up on Google, but couldn't find much. Anyway, this is the scene I think I remember:

Either the episode as a whole or just a portion of the episode had to do with an egg that Billy found, and he made plans to raise the egg "as his own" and hatch it like a mother bird would do with her own baby birds. Mandy and Grim then ask him how he's planning to do it, when we cut to a blurb inside of Billy's mind of what he pictures taking care of the egg would look like. We see him sitting on the egg of course, but it gets kind of funny and bizarre when we see him planning out birthday parties for the egg and attempting to feed the egg, all while it is still unhatched. Also, the representation of Billy in these daydreams is not his face, but actually his butt.

I've tried searching up this scene description online, and I've been given episodes that do include both Billy and eggs ("The Crawling Niceness", "Hill Billy", etc.) but I didn't see this scene included in them. Anybody recall seeing this scene? Or is it just something I could've imagined?