noun: A particularly creepy middle-aged peeping Tom who must always secretly video others doing sexual or lewd acts for his later enjoyment.
I found my Uncle's Dirty Donald videos; I was in them!
When you sneek up behind someone and rip a nasty, stinky, crunchy, wet fart on their back, leaving a streak of mud-butt.
Damn that was a Dirty Donald if I"ve ever seen one...wipe that off your back!!