I have heard of people taking one bottle of a cough syrup containing only DXM. They have claimed that was something they need to take to get high. It can be dangerous though, and I would not recommend attempting it.
1 Additional Answer
DXM is found in cold and cough medicines. You need less than a couple ounces or a full dose to get high. Remember that 8 pills can and will kill you as well as drinking a half a bottle of the stuff in one shot. Your weight plays a big part in this so stick with the recommended dosages and see what happens.