I've got a great link for some funny wedding toasts , I'll include it further down (just have to find it first).
And yes, I know that feeling very well unfortunately- I was clever enough to leave my wedding speech for the last night before the wedding! I might laugh about it now looking back but in that moment I really thought I was "finished" (I can't use the actual word). I panicked, wallowed in self pity and finally settled on disbelief.
Finally I had a brain surge and turned to the internet - googled funny wedding toasts , or it may have been funny best man speeches. Anyway, luckily I found Dan Steven's wedding speeches . With a small fee of only 19/20 dollars at the time (I didn't check - it might more now) which I gladly paid , I selected my toast according to my personality, the circumstances and the audience (didn't want to offend anyone with too outrageous stuff).
I copied most of my selected wedding toast, added some of the funny wedding toasts / jokes (there's plenty to choose from) included some personal info about the bridal party and the bride and groom, and anecdotes etc. Plus I had some extra jokes in reserve. I had the whole toast off in about 45 minutes. I think what really made it easy for me was having a structure to work from.
Immediately the pressure was off, and I could relax and concentrate on other things.
The speech went down a storm, I was told it sounded very professional.
Considering the ease, speed and peace of mind, I would do it that way again, no problems.
Good luck and I hope I helped with your search for funny wedding toasts.