When the moment of truth arrives, you must already be ready to shoot. The only advice I can offer echos what others have said, and adds a bit of humor. Grunt, whistle, speak, shout, holler, yell, heck...break wind if all else fails. <img src=icon_smile_big.gif border=0 align=middle>
Good luck with what ever you try. In these situations, trying something always outweighs doing nothing.