extempore

\ik-STEM-puh-ree\, adverb:
Without previous study or meditation; without preparation; on the spur of the moment; suddenly

--In the heat of the moment, the preacher launched extempore into a rendition of "Back Dat Ass Up." The crowd had been with him until that point.
--Traditionally, Dr. Herling liked to begin his film seminar by delivering drunken reflections extempore about his marital failings. "Always put stickers on your stuff," he would advise between whiskey burps. "Love comes and goes, but a limited edition vinyl print of Sargent Pepper's is forever."
--Grandpa may not remember any of our names, because he can still recite the entire series final of Quantum Leap, extempore. And dammit if that doesn't count for something!
--"But why don't you love me?" Bruce asked Sheila, not expecting her to respond quite the way she did; calmly and extempore, with an 8-hour long, nonstop marathon list of very specific and well-articulated reasons.