I had a friend in college who took some kind of super strong migraine medicine that made her unable to feel ANY pain. She took it once and then smoked and put her hand on a red hot burner on the stove to prove it.
We all thought it was a pretty cool party trick too! Until we sobered up the next morning and saw that her hand was one massive blister... Not having a car was a blessing, I got to skip the ER visit.