The opposite of a good idea would be a bad idea. Depending on how bad you could also say terrible idea.
an idea that is not good it is bad you shouldn't do it no matter what
it is a bad idea
Bad Idea was created in 2006.
it not rly a bad idea it help you
no its not a bad idea I think so
having an affair with anyone is a bad idea.
Some Good Idea Bad Idea quotes are "It is not a bad idea to occasionally spend a little time thinking about things you take for granted. Plain everyday things". or Minimum sales prices for alcohol are startlingly bad idea. As with excise duties, the effects are regressive".
yes it would be a vary bad idea
Yes, teasing a dog is always a bad idea.
A very bad idea. You will get into trouble at school if you try.
bad bad bad bad idea!!