your reaction to visual stimuli is really "normal". inconvenient yes. but normal. there is really nothing you can really do to keep this from happening unless you wear very dark glasses and quit looking at things that are "hot" to you. as you get older you may be able to control your involuntary erections since you will be busy and not be thinking about sex 24/7.
get boners easy. can i decrease visual arrousal? . whenever i see something. ahem "hot" i always get hard and want to masturbate. i'm 16 so it could just be the time in my life but is there anything i can do to help?