Is it normal to have an orgasm sun tanning on a hot day

I sun tan in a very very small tight bikini swimsuit. Every time I sun tan, I may not orgasm, sometimes I will after a long period of extreme pleasure, but even if I do not cum its a feeling of like pulses going thru my penis and thru my body. They can last for a minute or for a hour or hours. Depending on how intense it is it can cause me to cum on the beach. It is mainly caused from the hot sun. If a cloud comes in it will shut off like a switch. It is not super noticeable but if someone is watching super close they will be able to see my penis pulsing and my leg may quiver once in a while and I may give out a light moan from time to time. The swimsuit is so small and tight and can only stretch so much, which helps to conceal what is going on. You pretty much have to be looking between my legs to really see good. Luckily I tend to be a girl magnet most times when I go to the beach with groups of girls around me. And if I do cum, my penis starts jumping around like mad. It is uncontrollable, it just does what it wants and nothing can stop it. It takes all I can do to not moan to load and just lay there till it settles down or till i cum. I have had dozens of wonderful orgasms this way. I've had orgasms with girls 5 feet away from me, smiling at me after I came. Of course I just came so I cant help but to smile back at them. I have a very nice tan by the way.