Hello young man, Just relax, you are not suffering for any problem. This is normal thing happens to all man when passing phase from adolescence to adult. Normally penis get erection from external stimuli like porn movie,sex chat or talking to girlfriend initially. however its main cause of erection is sex center in your brain which activated during above all activities.According nature s law after this type of erection penis has to enter in to vagina for sex and to prevent friction some fluid secret from it when it is ready to enter. But in your case that is not next step and penis is not getting any physical touch , so brain revert back penis to normal position after that fluid discharge. As you grow up, your sensitivity to such stimuli will become somewhat decreased and you will not get this much fast erection and no discharge. And yes if you are not masturbating regularly, your semen stored in your prostate-testis in excessive amount, which can come out during this type of erection or even during sleep or urination. So regular masturbation can also help to prevent such incidence. Hope you got it. Thanks for using healthcaremagic. Hope I have answered your query satisfactorily. Regards, Dr.Chintan Solanki