My sperm or cum comes out after a short time when I think about sex. Without do anything it comes out. What can I do for it?
And also when I eat some sweets, that night my pants get wet. Why?
It isn't your semen that you are seeing. What you are seeing is pre-ejaculate fluid. This clear fluid is produced whenever you are aroused (thinking about sex). It prepares the penis for ejaculating semen by clearing out the tube in your penis and lubricating the tube. The dripping of the pre-ejaculate fluid can't be controlled.
I don't know if you are dripping pre-ejaculate fluid or having a wet dream when you eat something sweet. I suspect that the extra sweets is keeping you from sleeping as deeply, so one of the two is happening.