Me: I like Firefox over IE, it’s faster and includes neat features like private browsing.
Older Scouter: Private browsing?
Me: Yes, since you and your wife share a computer, you can use it to create a session where none of what you looked at will be stored.
Older Scouter:  I get it.*nods head and almost winks* I think I know why that was made.
Me: Oh? (please don’t say porn, please don’t say porn)
Older Scouter: Yeah, that way patch hounds like me can buy stuff on eBay without our wives knowing.  Whoever made this must have had us in mind.

Yes, elderly patch collectors are the EXACT reason that private browsing was invented.  An answer I’m sticking to so that I can avoid visualizing the alternatives.