Pick up your straw, and pick your first glass. Take your time.
Hmm. Interesting. okay. Now, remember, stick your straw inside the bag - make sure it's right down to the bottom! Use your other hand to seal the bag around the straw. Give the bag a little shake as well to get all the liquid down there.
Now you're going to close your eyes, bring that straw to your submissive little lips, and then take a big, huge, long suck like we practiced. Suck it all up, and then as quickly as possible swallow it down - the less taste there is, the less doubt you'll have, and the better off you will be.
Go for it!