watch wedding crashers and the wedding singer
Basically, make fun of your buddy a lot, praise the bride a lot, tell a funny story about your buddy from jr. high, and then close with mushy rant about how perfect the two of them are for each other. i've done this twice, both times with little or no preperation. It's a lot easier than you think. Just let it flow and make sure not to say "uuummmm" or "like" at all.
I suck at public speaking... can anyone help with a cool toast? Need it for Saturday.