Buffalo buffalo buffalo Buffalo buffalo buffalo buffalo buffalo.
into Japanese: バッファロー水牛水牛バッファロー水牛水牛水牛水牛。
back into English: Buffalo buffalo buffalo buffalo buffalo buffalo Buffalo buffalo.
back into Japanese: バッファロー水牛水牛水牛水牛水牛バッファロー水牛。
back into English: Buffalo buffalo buffalo buffalo Buffalo buffalo buffalo buffalo.
back into Japanese: バッファロー水牛水牛水牛バッファロー水牛水牛水牛。
back into English: Buffalo buffalo buffalo buffalo buffalo buffalo Buffalo buffalo.
back into Japanese: バッファロー水牛水牛水牛水牛水牛バッファロー水牛。
back into English: Buffalo buffalo buffalo buffalo Buffalo buffalo buffalo buffalo.
...
It does that literally 21 more times before saying this:
"It is doubtful that this phrase will ever reach equilibrium."
I win.