balls noises

Sounds emanating from a character's balls — including throbbing, sloshing, clenching, gurgling, or churning, among other sound effects. These are most often conveyed as written onomatopoeia, but may be audible within an animation.

While impossible in real life, "balls noises" are used to underline how pent-up or virile a character is, the size of their balls, that their testicles are "working" (creating more semen/sperm), or that their balls are expanding.