Lets talk about IT baby. IT, the movie featuring a group of kids known as the losers club and a clown known as Pennywise the dancing clown.

Before going any further I have to clear up one thing, this theory isn’t about Pennywise’s origin. That’s already been explained, he’s an interdimensional being who’s arch nemesis is the turtle
Yeah, like that.
I want to discuss Pennywise’s red balloon and its significance. Throughout the novel, movie and miniseries, the appearance of a red balloon is a way of foreshadowing that Pennywise is out to get you or he wants you to do something. So why red? Why not orange or purple or white? Well its because of what red symbolizes.
Red is the color of passion. Since Pennywise main means of luring his victims into a trap is by scaring them or making them hallucinate, then showing them a red balloon to get their adrenalin pumping is an easy way to make them more susceptible to his mind games.

I will deter from giving my usual hundreds of examples because the movie gives us 100’s of examples. In every scene that there is a red balloon, there is always a hallucination or an act of passion. Pennywise knows this and he uses it to his advantage.