The Condom Separator

Okay, listen up, you're clearly not the sharpest tool in the shed if you couldn't figure this one out. You post things on the internet anonymously so you don't have to face the consequences of your terrible thoughts. This "joke" is using the word "condom" to play on the expression "what a difference" or "what separates", the difference being made through the use of a condom. It is implying that one joke is not as "safe" or wanted as the other one. That makes it a pun.