I have a small bump (~1mm in diameter - oval shaped) on my scrotum which is creamy yellowish in colour like a pimple. It does not hurt unless squeezed but I can't seem to pop it like a normal yellow pimple (probably shouldn't try). When the scrotum "contracts", it starts to camoflage to the rest and only a bit yellow - much less noticeable. When the scrotum is stretched, it becomes much more visible.
It look somewhat like this when stretched except without the red/pink around it - this is when stretched.
I forgot to mention, it has not changed since the first day I noticed it (couple of weeks ago). Nor is it changing throughout the day or anything - it's quite static but I believe it came up quite quickly.