I was playing a rated game against a low-level GnuGo bot when Black made this invasion move. Looked very frightening, but turned out to be just a bluff.
(;C[Black has just placed the invading marked stone. Defend!]AB[aq]AB[ar]AB[br]AB[cr]AB[dr]AB[dq]AB[eq]AB[ep]AB[eo]AB[en]AB[em]AB[do]AW[ap]AW[bq]AW[cq]AW[cp]AW[dp]AW[co]AW[dn]AW[dm]AW[cl]AW[el]AW[ek]AW[ej]AB[fl]AB[fk]AB[fm]AB[bo]TR[bo]AP[goproblems]
(;W[bn];B[ao];W[an];B[bp];W[ap]C[RIGHT])
(;W[ao];B[cn];W[bp];B[an])
(;W[bp];B[cn];W[ao];B[an])
(;W[cn];B[bp];W[bn];B[ao];W[an];B[ap])
(;W[an]
(;B[cn]
(;W[bp];B[ao])
(;W[bn];B[bp]))
(;B[ao];W[bn];B[bp];W[ap]C[RIGHT])))
