Why do I laugh when getting my blood drawn

Im not saying this is a weird edgy way, but I just got my blood drawn and I couldn’t help but laugh uncontrollably. Whenever I looked at the needle and the blood I’d start laughing harder and harder, she even lost my vein cause I was laughing too much and kept moving around. It didn’t hurt at all either. This also happened when I got stitches on my fingers since ive cut three of them open. Every time I’d laugh super hard when they were stitching up the wound idk why. Does anybody know the reasoning behind this? I tried looking it up but I couldn’t find an answer.