Forum:Using flip effects

If man eater bug gets flipped up do you have to use its effect when its the only monster on the field or when your opponet has no monsters and you do. do you havr to use it on one of yours. and do you have to use graver keeps gaurd hwen it flips on your opponents monster or is it your choice?98.30.120.59 (talk) 01:11, July 4, 2011 (UTC)