1. the sensation that comes when one eats some spicy food (maybe some korean barbecue or a volcano box from taco bell) and takes a dump later on during the day, and feels as if his or her butt knew that the food was spicy.
2. a feeling burning around the anus after eating spicy foods and eliminating the resulting stool
note: the foods causing fire butt are not limited to spicy food.
"Hey, how's it going"
"Man, I had some volcano nachos this afternoon and I just took a deuce. Feels like my ass is on fire."
"You, my friend, have fire butt."
1. Taking on injuries like a warrior, possibly hitting multiple game winners and giving out 40 point performances to remind the haters that half of you is still better than two of them.
2. Sucking up pain and still going hard despite the pain.
1. Despite a index finger, back spasms, minor ankle problems, and a pinky finger that wasn't allowed surgery to heal correctly, Kobe Bryant Kobe'd through his injuries, supporting his team until finally receiving another, more serious, ankle injury. Realizing that Kobe'ing through it was no longer rational, he finally allowed himself rest.
2. "Shit, son, I might have sprained my wrist."
"Man up and Kobe through it!"