In tournament poker it is a violation of the rules in most rooms to show your hand to induce action. Under the TDA rules this could incur a penalty.

In a cash game, you should not be exposing a card like this unless it is heads up. If it is heads up in a cash game I don't see any problem with it and none of the rooms I have played in seem to have a rule against it. however there may be rooms with a rule against it so check before you do this.