Embarrasing Precum
I tend to have that problem. Even my wife trying on dresses in a store can be a trigger! Except for a C/O area, I don't want it to be noticeable. When nude, if it happens, it happens! A string down to my thigh may be the first thing I notice.
When wearing swimsuits it frequently happens and can be very obvious on solid colours, especially since there is little material to start with and they are a snug fit. In the past this has resulted in not just a wet patch, but a shiny bead of fluid on the surface of the fabric, front and centre. For many years in that situation I've used a condom over my whole package with a cock ring to help it stay anchored. That setup also makes for a great profile under the fabric. Things can get very slippery inside the condom after a short time but nothing escapes.
When in shorts, I just hope it is not noticeable and stick to dark colours. Concentrating on other things helps.