I’ve written before about the past participle of the verb to run; I’ve noticed a similar problem with the pattern of the verb to drink.
The present tense of drink is, of course, drink. He drinks eight glasses of water every day.
The past tense is drank. They drank champagne at midnight.
The problem usually comes when forming the past participle. I know that it’s tempting to avoid using the word drunk unless you’re talking about spending too much time with your buddies Jack (Daniels) or Johnnie (Walker), but in this case, avoidance is unnecessary.
The past participle of drink is (have/has) drunk, as in We have drunk the rest of the bottled water. She has drunk two cups of coffee. I have already drunk my morning tea. Do not say We have drank the rest…, she has drank two cups…., or I have already drank my tea.
Sherry
Paul’s book–Literally, the Best Language Book Ever;
Everything Language and Grammar 