ad-lib, ad lib, be caught napping, be surprised, be taken unawares, be unprepared, beget, breed, bring forth, bring into being, call into being, coin, conceive, concoct, contrive, cook up, dash off, design, develop, devise, discover, do offhand, dream up, engender, evolve, extemporize, fabricate, fake, frame, generate, give being to, give rise to, go off half-cocked, hatch, have no plan, improvisate, invent, jury-rig, knock off, lash up, make do, make do with, make up, mature, mint, originate, plan, play by ear, procreate, scrap the plan, spawn, strike off, strike out, think out, think up, throw off, throw together, toss off, toss out, vamp, whip up, whomp up, wing it