WordNet (r) 3.0 (2006):

whomp up
    v 1: prepare or cook quickly or hastily [syn: whip up, whomp
         up]

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "whomp up":
   ad-lib, assemble, bat out, botch, build, bungle, cast, compose,
   compound, concoct, construct, cook up, create, dash off, devise,
   do anyhow, do by halves, do carelessly, do offhand, elaborate,
   erect, evolve, extemporize, extrude, fabricate, fake, fake up,
   fashion, form, formulate, frame, fudge together, fudge up, get up,
   improvisate, improvise, indite, jury-rig, knock off, knock out,
   knock together, lash up, make, make up, manufacture, mature, mold,
   patch, patch together, patch up, piece together, play by ear,
   pound out, prefabricate, prepare, produce, put together, put up,
   raise, rear, rough out, roughcast, roughhew, run up,
   scrap the plan, set up, shape, slap up, strike off, throw off,
   throw together, toss off, toss out, toss together, trifle with,
   vamp, whip up, wing it, write