My sister and I would watch the Power Puff Girls when we were younger, and in the Theme Song, this Speech Bubble (now I realize it's probably a sound company or something) would come up, and we thought that meant that we could talk to the television charactors while that symbol was up. We would say things like 'Bubbles, you're my favourite!'
We still joke about this from time to time.
A childhood belief about tv shows

others believed things like this
- I used to believe the sound of a flushing toilet was nearly identical to the 90210 theme. — Laurenne
- last time when the television was on i thought the people were performing in it -.-
— irritated kid - I use to believe the sound that a car made when it was running low on gas was what they called horse power...— Bianca
- This may sound absurd but I thought the numbers next to the Bible versus said what time the person said it at!— Biomeka
- I used to think that the actors on tv shows sang the show's theme song.Anon
- Until I was about 15, I beleived my Father was the person who sang the "Cheers" TV Show Theme Song.— Dustin