Actually it'll only be good if you're interesting. This might help it not be terrible though
  1. This wedding is not about you
    This is not a showcase for you to try material or whatever.
  2. No one is getting 'locked down'
    The bride and groom are in love or some approximation of it. No dumb 'party time is over' jokes
  3. Talk about the bride
    The woman beside your buddy is a real human being whose wedding you are at. Don't ignore her in favor of an anecdote about high school. If you don't know her do some research.
  4. Don't flirt with the bride/anyone's mom/anyone's grandma
    Dudes occasionally thing this is a funny or charming move but it's gross and annoying. Cut it out.
  5. Say something specific about the couple
    By the time you get to talk everyone at this wedding will have already heard 900 cliches about the nature of love in the abstract. Come up with something you can say about these 2 people--a memory, a moment, something nice.
  6. Get off stage
    As quickly as possible. People wanna eat/drink/dance
  7. Stay sober
    Suggested by @wikiHow