What Goes In, Comes Out the Same

Below is a rather disgusting conversation between myself and my cousin, or rather, I should say, it's mostly herself. Cousin: Guess what? Me: Huh? Cousin: I shitted twice last night. Me: Ok... Cousin: The second time, I did it, I notice some small white stuff floating on top. Me: ??? The word fungus popped up in my mind. Cousin: I stared at them for a while trying to link it with the food I ate in the day and guess what??? Me: What? Cousin: It's sesame seeds!!! You know we ate MacDonald's in the morning right? It's the seeds on top of the bun! I ate McChicken...