It only takes a second for the pill to dissolve. If someone offers to buy you a drink, go with them to accept it. Do not take open beverages from someone who you don't know very well or don't trust. Never drink anything out of a common punch bowl. More than one attempted date rape has been prevented by watchful friends.
Date rape is a serious issue.
It is one that affects many, many young people. Knowledge and awareness are important tools in preventing this from happening to you.