Don't tell me your idea is great; pitch the idea so I can fall in love with it.

Don't tell me your joke is funny; deliver the joke and let me laugh.

Don't tell me your cookies are delicious; give me one (better yet, five) to try. 

If you believe in your idea (or your joke, or your cookies), then you don't need to tell us how great it is. If anything, sharing your own rave review can put us in a skeptical mindset: he thinks it's so great? We'll see about that...

Have the confidence to let your idea speak for itself. If it's great, we'll know it. If it's not, we'll still want to eat the cookies.