How can I lose about 5 lbs by saturday?!

Well any quick "weight loss" will simply be water weight and you'll gain it back. But you asked how to do it.

I am not recommending this at all so beware that it can be dangerous.

Basically if you buy a rubber suit and or use a plastic garbage bag and start running, you can lose a lot of water weight. A sauna will help you drop more water weight as well.

I know this b/c I used to wrestle in high school. It's no fun though and the weight comes right back on. I dropped about 7-8 lbs in close to 24 hours. It wasn't pretty i'll tell ya.

get a time machine, go back 2 weeks and do some excersice.

5lbs will not make you look any different, so don't bother.

Sauna / steam bath / turkish bath

Cut your leg off

just a dumb thought