My father told me that his most profitable “deal” was written out on the back of an envelope and that was that.
They reportedly managed to get a DNA sample from an envelope the mother had licked.
And pushing the envelope, as she always did, with a playful, anti-authoritarian attitude—up to a point.
envelope en·ve·lope (ěn'və-lōp', ŏn'-)
An enclosing structure or cover, such as a membrane or the outer coat of a virus.