Is *this* the best they can do?

I saw one of these bumper stickers yesterday on the commute into work. I have to say, is this as creative as the Left can get these days? It took me 10 minutes to figure out what they were referring to, and even then, I had to Google the date to figure out if I was right. If this is supposed to be some kind of protest, it is spectacularly ineffective. If it is supposed to be an inside joke... well... I just don't find it funny.

Maybe if they had stickers like this while President Clinton was in office, I would have gotten it. But then, I have never considered "sour grapes" to be a comedy style.