I know what you were feeling.
I had the same problem wearing swim trunks, the older kind that were short cut and light weight fabric, and when they were dry I had no lump.
When wet they clung to me and if the water was a little cold what I have disappeared and all that was showing was a nub if that.
I solved my embarrassment by wearing cut off blue jeans. The fabric is thick enough and my nub didn't show that well.
