expression
even so; however; still; nevertheless; on the contrary
Emphatic version of ところが, used to strongly contrast with what was expected. Often has a colloquial, slightly dramatic feel.
See also: ところが
彼は失敗すると思った。ところがどっこい、見事に成功した。
I thought he would fail. But lo and behold, he succeeded brilliantly.
もう終わりかと思ったら、ところがどっこい、まだまだ続くよ。
I thought it was over, but no, it's still going on.