off·hand 
(ôfhănd, ŏf-)
(ôfhănd, ŏf-)adv.
Without preparation or forethought; extemporaneously: Offhand, I can't think of his name.
adj. also off·hand·ed (-hăndĭd)
Performed or expressed without preparation or forethought: an offhand suggestion.
offhanded·ly adv.