Taken from one of my own KGS games where I was playing Black and my opponent missed his chance. I undoubtedly missed some variations, so please, don't hesitate to point them out!
(;AB[cp]AB[bn]AB[dp]AB[cl]AB[dl]AB[dj]AB[ck]AB[bj]AB[ak]AB[gp]AW[cn]AW[dm]AW[el]AW[ej]AW[ci]AW[cj]AW[bi]AW[di]AW[bg]AW[hj]AW[fg]C[How can White take care of this mess?]LB[gn:Tenuki]AP[goproblems]
(;W[gn]C[];B[bo]C[You missed your chance!])
(;W[cm];B[bo];W[bm];B[am];W[bl];B[bk];W[dk];B[al])
(;W[bm];B[bo]
(;W[cm];B[am];W[bl];B[bk];W[dk];B[al])
(;W[bl];B[cm])
(;W[am];B[cm]))
(;W[bo];B[ao]
(;W[ap];B[co]
(;W[an];B[cm]
(;W[bm];B[dn])
(;W[dn];B[bm]))
(;W[bp];B[bq];W[an];B[cm]
(;W[bm];B[dn])
(;W[dn];B[bm]))
(;W[bm];B[bp];W[cm];B[am];W[bl];B[bk];W[dk];B[al])
(;W[cm];B[bp];W[bm];B[am];W[bl];B[bk];W[dk];B[al]))
(;W[bm]
(;B[co]C[Black has made a grave error! How to benefit?CHOICE]
(;W[an];B[cm]
(;W[em];B[dn];W[bn];B[bp]
(;W[bl];B[al];W[ap];B[bk])
(;W[ap];B[bl]))
(;W[bn];B[dn];W[em];B[bp]
(;W[bl];B[al];W[ap];B[bk])
(;W[ap];B[bl]))
(;W[dn]C[Dead as a doornail!RIGHT]))
(;W[cm];B[am];W[an]C[This is a two-step ko favorable to White!RIGHT])
(;W[bp];B[cm]
(;W[an];B[dn])
(;W[dn];B[am]
(;W[bl];B[an];W[ap];B[al];W[bq];B[cq];W[br];B[cr]
(;W[bs];B[ar];W[ai];B[cs];W[aj];B[bk];W[dk];B[as];W[aq];B[ar]C[Getting greedy, aren't we?])
(;W[as];B[cs];W[ai];B[bs];W[aj];B[bk];W[dk];B[ar]C[Getting greedy, aren't we?])
(;W[cs];B[ds];W[ai];B[bs];W[aj];B[bk];W[dk];B[ar]C[Getting greedy, aren't we?]))
(;W[an]C[This is a two-step ko favorable to White!RIGHT]))))
(;B[cm]C[CHOICE]
(;W[an];B[dn])
(;W[dn];B[am];W[an]C[This is a two-step ko favorable to White!RIGHT])
(;W[co]
(;B[am]C[CHOICE]
(;W[bl]C[This move allows too many variataions, more than I have time to input. Feel free to explore; I'll count as correct.RIGHT])
(;W[an]C[This is a two-step ko favorable to White!RIGHT]))
(;B[bl]C[CHOICE];W[an];B[am];W[al]C[This is a two-step ko favorable to White!RIGHT]))))
(;W[bp];B[co]
(;W[cm];B[bm])
(;W[bm];B[cm]
(;W[an];B[dn])
(;W[dn];B[am]
(;W[bl];B[an];W[ap];B[al];W[bq];B[cq];W[br];B[cr]
(;W[bs];B[ar];W[ai];B[cs];W[aj];B[bk];W[dk];B[as];W[aq];B[ar]C[Getting greedy, aren't we?])
(;W[as];B[cs];W[ai];B[bs];W[aj];B[bk];W[dk];B[ar]C[Getting greedy, aren't we?])
(;W[cs];B[ds];W[ai];B[bs];W[aj];B[bk];W[dk];B[ar]C[Getting greedy, aren't we?]))
(;W[an]C[This is a two-step ko favorable to White!RIGHT]))))))