Well, here it sure LOOKS LIKE a couple of testicles, but it does have other meanings as well, like e.g. "balls" in favorite toys. Many don't even know about other kinds of balls than the ones their dogs covet and insist on playing with, over and over ....
Yes, that's cute: A charming dog with his/her favorite toy, i.e a BLUE ball
However, as most of us know, and as my first picture indicate, the saying "Blue Balls" may have another meaning than being the name of favorite toys for a dog. Also they may be the name of what is known as painful testicles, and as such they are feared by many men and some women. The men fear what many present as an excruciating pain, and the main reason why some women fear them is that these bouts of pain are used by some men to make them take part in sexual acts they don't really want to have anything to do with. Actually, women may tell you that the love and care for men and boys which they were brought up to feel will get them to help the male sex to the orgasms which rid them of their painful "blue balls". I see it as a common male trick, something that shouldn't oblige women to do anything, but many of the female sex feel so bad for their menfolk that they may comply, no matter what.
Yes, the cure is an orgasm, but still, that shouldn't be the responsibility of a woman. To me it's some kind of "rape": The man may not attack the woman physically, but he uses the myth of the super-painful "blue balls" against her. She, who most probably has been conditioned to take care of the vulnerable male ego and support his feelings of "maleness" and "masculinity", becomes an easy prey for the allegedly victim of the blue balls syndrome. Something that's not OK in my opinion ....
https://health.clevelandclinic.org/blue-balls
https://www.healthline.com/health/mens-health/blue-balls
https://bigmouth.fandom.com/wiki/Blue_Balls
https://www.webmd.com/sex/blue-balls
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10155057/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10155057/
Wikipedia