When is the only time boy’s sperm come out? Questions › Category: Questions › When is the only time boy’s sperm come out? 0 Vote Up Vote Down wyattg asked 6 years ago A boy’s sperm comes out when he ejaculates. This can happen any time he is aroused and gets sexually stimulated. This can happen when he is having sex, but it can also happen without a partner. Please login or Register to submit your answer Username or Email Address Password Remember Me