Refering to the making, pouring, or drinking of "Syrup", which is a mix of pop and promethazine with codeiene. "Syrup" induces a very slow paced "high" such as the movements of a turtle. "Syrup" may be refered to as "Purple Drank" or "Sizzurp" which is a mix of pop, promethazine with codeiene, and crushed up oxycottons. To recap, if someone says pour me a four, well than you know what they mean.
Just listen to Lil Waynes's "Me and My Drank", that is all an example of Four.