With the opinion of the average human on the prospect of speaking in front of a crowd, odds are fair that someone is going to be very dull. If you want to lessen the odds that it will be you, you're going to need to navigate a very tight channel.

Don't worry about the little old ladies. It's whoever your best man is walking out of the ceremony is that you need to worry about. You're reflecting on this guy. He volunteered you for a fair bit of very subtle responsibility. These little speeches will be remembered. Drunken slurred best man speeches from fifty years ago are still remembered with crystal clarity by those witnesses present.

Even so, this is no time to be timid. You're participating in a very important event in your friend's life. This is a time to show him that you'll remember those times past, and that you anticipate good times ahead for him.