So, if you put two stars far away from another (As in, not closely together like in a circumbinary system), and you put a planet (Gas giant for more visible effect) on one of the stars, the terminator line would look weird, zig-zag, it just looks ugly. Here, let me show you :
This seems to only happen to me. Here's a post by SyzygyΣE, which shows a normal terminator