Great stage, parlour or cabaret opener (or anytime in your show).
A card is chosen from an imaginary pack of cards by a process of elimination using many members of the audience.
This imaginary card is then placed into an imaginary little coin envelope.
You remove from your pocket a white unsealed envelope which you show to be empty.
The spectator holding the imaginary envelope throws theirs towards your envelope, you pretend to catch it and seal it inside your real envelope.
When you open the envelope a real coin envelope is now inside and inside that is a real playing card, the one they chose.
Can be performed surrounded.