As best man, one of your duties is to give a best man toast during the reception. This means you'll have to talk in front of lots of people whether you like it or not. Therefore you should have something prepared so you won't be as nervous or make a fool of yourself. While you can talk about anything you would like there are a few rules you should follow to ensure your speech is not only appropriate but also memorable.

Do not embarrass the bride
This is the cardinal rule and one that cannot be broken unless the bride happens to be your sister and even then it's questionable because this is her big day. Don't make her feel uncomfortable or awkward, she shouldn't have to think about anything or have any insecurities on this day. While you may crack jokes about her other days, take this one day off and find something else to talk about, no matter how you truly feel about her or the marriage.

Don't toast drunk
Yes it's true most guys drink before the ceremony or at least before the reception has actually started so you're likely to be feeling a little happy or at least more relaxed at this point. But don't stand up and start talking if you're drunk. So in other words, wait until after the best man toast to get drunk. A toaster who is drunk as a skunk is obnoxious and your slurred speech could reveal something that isn't meant to be said or known. It could also just make you look like an idiot. Believe it or not lots of drunk best men have revealed things like the reason the couple was getting married was because she was pregnant and none of the family knew! Don't cause drama, stay sober until after you're done talking and then you can hit the bottle and start the party.

Keep the past in the past
If the groom has a crazy story about his single days and so on keep it in the past, this isn't the right time to bring it up. So use some discretion in choosing what stories to tell and how many details you decide to spill out because it may get the groom in trouble with his new wife otherwise.

Keep it short
Make your best man toast relatively short because if it runs on too long people will be bored and they have either already listened to other toasts and speeches or will listen to more so spare them a bit and get to your point as quickly as possible.