For when you REALLY don't know when to use "you're" or "your".
Can be turned around to
be clever if it is applicable both as a
possessive and as the short form of "you are" (example 1);
humiliating otherwise (example 2).
Example 1 - when one is in possession of a homosexual whilst also being one themselves.
Kevin: "What did you just say?"
Melvin: "
You'r gay."
Example 2 - when you failed
Grade 1 English.
Melvin: "That's not my homework, it's YOU'RS"