blue balls

noun[plural only]3

1. •
   (slang) A cramp-like ache in the testicles and prostate region caused by prolonged sexual arousal; testicles experiencing such an ache.
2. •
   (slang, figurative) Unfulfilled sexual desire.
3. •
   (slang, old-fashioned) Buboes (in a person of any sex) caused by a sexually transmitted infection; the infection that causes them.

   • [...] away the flesh and cause ulcers and buboes (blue balls). — 1920