The Little Pea Can
This effect is simply, somewhat PG, but a great little pocket effect! A spectator is asked to think of one of three items - a pea, navy bean, or piece of popcorn.
All three items are put into the can. (S)he is asked to hold out his hand and concentrate on the item he selected. You then un-cork the can, and pour the contents (water) onto their outstreatched hand as you say, ''you were thinking of the pea.'' (The actual spelling would demand that an 'E' be substituted for the final 'A').
It matters not what he was thinking of, you'll get the laugh.