Ad lib -- doin' what comes extemporaneously

from www.wordsmith.org

ad lib (ad LIB) [From Latin ad libitum (at pleasure).]

• noun Improvised speech or music.
• verb tr. To perform music, speech, etc. spontaneously.
• verb intr. To improvise.
• adjective Improvised, impromptu.

"From delivery of scripted material to covering slip-ups to ad-libbing, Aznil is probably one of the few in the business who has a sixth sense, comedy wise."
-- Awards: Wide-skrin Disasters at Anugerah; Malay Mail (Kuala Lumpur, Malaysia); Aug 28, 2003.