It's a very informal and somewhat slangy way of expressing affection or possessiveness. It's often used in a romantic context, but can also be used playfully between friends.
Here are some examples of how it might be used:
* "Tú pa' mí, siempre." (You for me, always.)
* "Ella es tú pa' mí." (She is you for me.)
* "Este disco es tú pa' mí." (This record is you for me.)
It's important to remember that this phrase is very informal and may not be appropriate in all situations. It's best to use it only with people you know well and who you feel comfortable using informal language with.