I will be tested on wed and want to know if I drink this weekend if there's and thing I can do to help flush my system

Lots of exercise, run several miles a day, drink a lot of water and pray.

Most will have little effect on.

And know when you drink that it is so important to drink you will risk what ever it is that you are being tested for. Jail or child custody or a job are the common ones.

So if being locked up for probation violation, or losing custody of your kids, or losing your job is not that important. Go for it, "cheers"