If you have an autosiphon, that works. If not, do what I used to do: attach your racking tube to your racking cane. Sanitized, of course. Stick the end of the cane into the beer. Suck on the other end until you fill the tube up.
Put your tongue over top of the end of the tube, and quickly pull the cane out and release the liquid into another container. As long as your tube is long enough, you should get enough for a sample.
Now, after having read that paragraph, go back and read it again. Oh, hell yeah. Pure poetry. Just don't squirt it on her eyelash. Heeeeheeee.