noun
poorly played game of Go; amateurish Go
Colloquial term for a Go game played by weak or careless players, often full of obvious mistakes. The prefix ざる (from ざる 'basket/strainer') implies 'full of holes' or 'leaky', i.e., full of oversights.
あの二人の対局は、見ていられないようなざる碁だった。
The game between those two was such a poor Go match that I couldn't bear to watch.
初心者同士だと、どうしてもざる碁になりがちだ。
When beginners play each other, the game tends to turn into a leaky, mistake-ridden match.
Compound of ざる (zaru, 'bamboo basket/strainer', implying something full of holes or leaky) and 碁 (go, the board game). The term likens a poorly played Go game to a leaky basket, full of gaps and oversights.