I'm feeling a slight pulsing pain in my testies. What does this mean?

Several things. Symptoms and concerns like these mandate a thorough evaluation by your doctor. Only after such an evaluation, which may include labs and radiographic examinations, can he/she let you know what's going on and how best to help you.
It means it's time.. It means it's time for a trip to the doctor. Testicles should not pulse or ache for no reason, so a primary care doctor can check, refer to a urologist, and send for a testicular ultrasound scan if needed. Testicle aches and pains can be due to too much motion during sports (lack of a jock strap), an inguinal hernia, prolonged erections, trauma (getting hit/kicked), infection, torsion, etc...