system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some foods seem to "go right through you"?

I think Taco Bell would be the place that comes to mind most with this title but why do some foods seems to slide right through you when others seems to take your normal digestive cycle to be processed?

EDIT: WOW! Thank you for my first award!  All the comments have been a joy to read through.  I've laughed and learned immensely.  Thank you, thank you, thank you all.
gpt
Your GI tract does a lot more analysis and evaluation than you expect. 

When you eat something that makes your gut decide, "Nope, this is toxic." it will release instructions to the entire GI tract that more or less translate to, "MAKE WAY!"

So it's not actually the Taco Bell that you're passing a couple hours later, it's a meal or two before. Your GI is just greasing the wheels so that it can get whatever is in the Taco Bell that it doesn't like out as soon as possible.