With little or no preparation or forethought:
— An extempore skit.

synoniemen: ad-lib, extemporaneous, extemporary, impromptu, off-the-cuff, offhand, offhanded, unrehearsed.

Without prior preparation.

synoniemen: extemporaneously, extemporarily.

Roget 113: instantaneously etc. adj.; in no time, in less than no time; presto, subito^†, instanter, suddenly, at a stroke, like a shot; in a moment etc. n.. in the blink of an eye, in the twinkling of an eye, in a trice; in one's tracks; right away; toute a l'heure [Fr.]; at one jump, in the same breath, per saltum [Lat.], uno saltu [Lat.]; at once, all at once; plump, slap; at one fell swoop;" at the same instant etc. n.; immediately etc. (early) 132; extempore, on the moment, on the spot, on the spur of the moment; no sooner said than done; just then; slap-dash etc. (haste) 684.    ... meer laten zien

Roget 132: early, soon, anon, betimes, rath^†; eft, eftsoons; ere long, before long, shortly; beforehand; prematurely etc. adj.; precipitately etc. (hastily) 684; too soon; before its time, before one's time; in anticipation; unexpectedly etc. 508.    suddenly etc. (instantaneously) 113; before one can say 'Jack Robinson'," at short notice, extempore; on the spur of the moment, on the spur of the occasion [Bacon]; at once; on the spot, on the instant; at sight; offhand, out of hand; a' vue d'oeil [Fr.]; straight, straightway, straightforth^†; forthwith, incontinently, summarily, immediately, briefly, shortly, quickly, speedily, apace, before the ink is dry, almost immediately, presently at the first opportunity, in no long time, by and by, in a while, directly.    ... meer laten zien

Roget 134: opportunely etc. adj.; in proper course, in due course, in proper season, in due season, in proper time, in due time; for the nonce; in the nick of time, in the fullness of time; all in good time; just in time, at the eleventh hour, now or never.    by the way, by the by; en passant [Fr.], a propos [Fr.]; pro re nata [Lat.], pro hac vice [Lat.]; par parenthese [Fr.], parenthetically, by way of parenthesis, incidentally; while speaking of, while on the subject; extempore; on the spur of the moment, on the spur of the occasion; on the spot etc. (early) 132.    ... meer laten zien

Roget 612: extempore, extemporaneously; offhand, impromptu, a limproviste [Fr.]; improviso^†; on the spur of the moment, on the spur of the occasion.