As a non-native speaker, you have to sound it out. It's a pun of "can't have your cake and eat it".

HN has been overrun with puns and attempts at humour in the past few years, while substantive comments have declined imho. But that's just the way it is.

Ha, OK. The darts seem designed to separate from the fletched part of the shaft, like a two-stage rocket, so the pun sounded confusingly truthful, as in they're not quite hafted.