Same definition as ex with benefits. Word play with Eggs Benedict's colloquial from eggs-benny(ies).
Interestingly similarity with the dish and the ex. Both are occasional, comfortable and familiar.
Great weekend, had the ex-benny over for lunch, she spent the weekend if you know what I mean.
It's not easy when they've got their ex-bennies, they get it all and no commitments, how do you compete?