It's part of the quote " he thrusts his fists against the posts and still insists he sees the ghosts" from the book/movie It. It's said by Bill, a main character who stutters, as a speech exercise. He later uses these words to help him defeat Pennywise. The quote isn't necessarily about stuttering, but I like the idea that this phrase that is used as a speech exercise can also be wielded as a weapon against fear. Bill still stutters, but these words give him power. So it's a tribute to a horror franchise I love, and it makes me feel empowered as a person with a stutter. That and I think it looks cool.