решать немедленно(have good ideas and make decisions quickly (Macmillan's Dictionary): Think on your feet! -- Решай немедленно! Решай не откладывая! (что делать)ART Vancouver)
шустрый(One of the funniest and thinking-on-his-feetest comedians in Ireland, Karl is probably best known in Ireland for his TV series Karl Spain Wants A Woman which was a huge success in that he not only got huge ratings but he also found himself a woman. VLZ_58)