text: what age do guys start to ejaculate? i'm 13 years old and when i ejaculate only semen(or watever the clear sticky stuff is) comes out. i want to know how much longer until sperm starts to come out when i ejaculate well, i'll try to be clear. yes, it's semen (and only it!) that event is called male orgasm and it occurs when the excitment reaches the apex. mind sends signal and from prostate and testicles (and from other glans too) semen begins to come out (through the urethra). it's a fast event lasting few seconds even. and after 1 -2 min. penis become flabby again. i hope to have satisfied your question.