If since birth you've eaten nothing but unsalted crackers and chicken broth like you're always 24 hours away from a colonoscopy, then yes, Taco Bell may cause you to explode. Taco Bell doesn't serve engine parts wrapped in shoe leather -- you should be able to digest something as basic as beans and cheese without being crippled into the fetal position on your bathroom floor as bursts of poop spray out of you. A burrito is not a big deal.
Not Taco Bell.
Yeah, you might be a little gassy afterward, but if you get diarrhea after eating Taco Bell and it's not related to food poisoning, you probably aren't long for this world. A taco destroyed your body and now your insides are melting. A goddamned taco. If the old "Taco Bell gives me the shits" joke perfectly describes you, you are weak. It's not a healthy meal, but it's not like they're getting their meats and cheeses out of another restaurant's hot dumpster. Their weird, corporatized Tex-Mex-style cuisine is fine. It's you -- the joke is on you and your piss-poor constitution. Much like Dorothy could always get home from Oz even without her special shoes, you need to recognize that the diarrhea was inside you the whole time.