Welcome mtipper! Definitely agree with the sentiment of keeping your speech short. If you can tell a story about you and your friend that shows your friend in a positive light, you'll do just fine.

Also, if you go that route, I wouldn't try to memorize it, just think about the highlights of the moment and cut out any parts that you think are inappropriate. That way, when you're speaking you'll be looking at the guests and the groom/bride instead of a piece of paper.

As always, easier said then done so good luck!