Three Shell Game Telepathy (Chazpro)  

Three cards are shown, each with a walnut shell printed on one side.
One of the cards has a pea printed on its face.  The cards are mixed
and placed into envelopes.  The spectator mixes the envelopes until
even they do not know where the pea card is.  All this is done while the
magician's back is turned.  Once the performer turns back around he is
able to always locate the walnut shell with the pea!

No confederates used.  This is a true one-person effect.  No magnets,
no electronic devices, no window envelopes, no subtle peeks of any
kind, no alcohol, etc.

You'll really love the simple but perplexing method!  It's based on an old,
diabolical, and greatly under-used principle in magic that's credited to
Tan Hock Chuan back in 1938.