Requires:
Musical instruments
Improvisational talent
A deck of cards
First, get yourself a band of friends and sit down with your instruments. Declare the characters you will be playing so that the others will be able to properly judge you later. One person is the Barkeep, describing the ruffians that come in and make trouble. Invariably, it seems, anyone who walks in the bar is looking for a fight (or a debt or a bounty, whatever the Barkeep deems) and with a player no less. The Barkeep will draw a card and describe a foe who’s picking a fight with the player to the Barkeep’s left (then to the left of him, etc). The player must then play a riff - a few bars, or longer if the group desires - that fit the character and the drawn card’s theme; the group decides democratically what fits or not. The consequences for failing are varied but often dire. Once you’re out of cards, it’s closing time. Go home.
A - Fast: 144+
2 - Minor
3 - Drawn out
4 - Arpeggio
5 - Bluesy
6 - Legato
7 - Stacatto
8 - Syncopated
9 - De/crescendo
10 - Chromatic
J - Forte
Q - Includes player’s highest known note
K - Lowest known note
Impractical, maybe impossible, for most? Sure. Awesome idea? Definitely.