The testicle or testis is the male reproductive gland in all animals, including you humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testosterone. Approximately 300 million sperm cells are produced daily, with millions made every minute. Your testicles are housed outside the body, and are therefore very vulnerable to extrmeties, as well as being subjected to being kicked. While hilarious, it does not lead to successfully conducive reproductive capabilities.
I would like to create my own humanoid species without this design flaw, but modeled off of your species, and have the testes inside the body rather than out. However, there is a problem. Too much heat is deadly to sperm. The body's temperature would kill the millions of sperm being produced, effectively making males sterile.
How can I get past this conundrum?