Punning French reference (appeared in one French movie, I forget which) to rubbishy food, especially oversold rubbishy food. A poubelle is a rubbish bin. Hence poubelle cuisine as opposed to nouvelle cuisine, geddit?
There, and we take the scrapings from the bin liner, mix it in with a few tabs of stale butter, microwave it for five minutes and they won't know the difference. Voila, poubelle cuisine.