ejaculating

How do I make these erections stop!?!

chris10
asks:
I'm 16, I get erections very easily. When I make out with girls I get them, or if I massage private areas not meaning her vagina. I notice when we're done that I have ejaculated. I don't even feel this happen. I don't feel super excited it just happens! I try to think about different things but it doesn't work! I hope you can help, thanks....