You can also try thinking of very cold water to help it go down.
You turned on devil, you're just like every other teenaged boy. There's nothing to be ashamed of, it's completely normal. It should be a compliment to any girl who causes it to happen. When I was a teen I had one girlfriend who loved to see it. Since I couldn't stop it from happening, she said it made her feel powerful. Girls certainly know they have that affect on us and they like it.
When I was in my 20s I was visiting a married friend who had a 12 year old girl at his house who had been baby sitting for him. I had to go past her house to get home so I agreed to give her a ride. We were all sitting around the kitchen table talking and she was sitting on various laps. I had to shove her off because she was giving me a lap dance. I couldn't believe it, but she knew exactly what she was doing and she was good at it. I wondered where she learned to do that at 12. Was she doing that at home to her father or an older brother just for kicks?