On your testicle sometimes there is kinda like a third testicle growing on one of your testicles and sometimes it is there and sometimes not its like bolloon filling with air every once in while?

It sounds like you might be describing a condition known as a hydrocele, which is a fluid-filled sac that can form around the testicle, leading to swelling. This can sometimes fluctuate in size, giving the appearance of a "third testicle." However, it's important to consult a healthcare professional for an accurate diagnosis and appropriate treatment, as other conditions could also cause similar symptoms.