When hitch hiking it is always a good idea to carry a beer, especially if you are a Kayaker or IK.
You see, everyone knows Kayakers will always take the last beer, so holding up your beer (instead of your thumb) should provide better results.
It also helps if you are wearing pants of some sort. While river folk will understand, they will also spot you for a Kayaker and may shy away from offering a ride. Non river folk will certainly be put off if you are less than clothed, even if you are holding a beer up.