To really understand the shittiness of this post, you need a bit of context. Many East Asian languages rely heavily on onomatopoeias to imply actions and verbs. Gulu gulu (also often written guru guru) is the onomatopeia that represents a tumbling sound, like something being tossed around in a rotating container. Essentially, it implies the verb, "churning." The post is basically saying that it will make your stomach churn and give you a stomachache.