the finger of choice, usually used by a man, to scratch his other end. causing the finger to sometimes become stained and/or smelly. thus the term poofinger
the customer counted his change with his brown stained poofinger.
my god you hand stinks like ass, did you wash your poofinger today?
In software development : poofinger - not providing a feature the user expects as a given. Missing out basic functionality. The opposite of adding sizzle to an app.