When getting a massage, sometimes the way the massagist touches my body results in spontaneous and unwanted arousal, which then might result in a visible wet spot on the underwear. (Not ejaculaton, this is easy enough to control, it's rather the Cowper’s fluid over which I have much less control.)
Important to mention: this is not an erotic massage. It's performed by a professional masseur or masseuse. (Both might cause me such reaction, it doesn't matter and it's not due to sexual attraction.)
I did try to avoid it by various methods (thinking of totally unrelated things during the massage, relieving myself shortly before, etc.) but failed, it appears to be purely physical reaction of the body.
My question is: when such thing happens, is there a way to hide the wet spot? So far when it happened the massagist didn't show any reaction at all, as expected, but it was very embarrassing.