Learn English – You say something but you don’t really mean it: an adjective to describe that offer or a phrase

Consider using the adjective causative.

There should be a comparable English idiom, but there isn't.

If it were me, I see nothing wrong with following the example of (a mere) twelve instances in Google in which a (probably Dutch) author used the English translation of the idiom in an English context.

The idiom, translated as a cigar from one's own box, is self-explanatory enough in my opinion that I would feel comfortable using it without scare quotes or any other apology.

From this link:

It is an impressive amount of technology, but it seems completely operator-driven. To a certain extent, it is a complicated way to serve the users a cigar from their own box!