Birds in my nest
When a guy says this it means he came in his pants and his genital regions got sperm on it.His pubic hairs in this area have been covered in sperm and now have dried up creating a nest.
Guy says :There are birds in my nest
Person next to him: what are you talking about?
Guy says: You don't wanna know
Person next to him: what are you talking about?
Guy says: You don't wanna know