Perhaps it might happen when a large enough portion of food is digested in the small intestine versus the stomach. Just a guess.
Spicy food doesn't cause me flaming butt, but it does give me heartburn now that I have hit my 30's. Large quantities of margaritas has always given me a flaming butt, mainly that jef fuel they served at Tia Maria's during the 90's.
I hate eating foods that aren't spicy... they all end up tasting like that bland cafeteria crap. Gotta have spices, gotta have heat. Oh, and those artificially flavored heat cheetos or whatever are nasty. Y'all want real heat via chili powder, buy some Death Rain Nitro and put it on your foods. If you want even hotter, get some habanero hot sauces/extracts. Now those could blow you a 2nd rectum. http://www.hotsauceblog.com/hotsaucearchives/review-blairs-death-rain-nitro/