Probably too old, but I just heard now. This came from a spam that went through and, by pure curiosity, I started reading:
l am dating a much younger woman (21). Before we began dating I was hearing stories of guys younger than me taking Vitamin V.
Yes, V is for Viagra. The honorable Urban Dictionary has an entry. Apparently, some people other than Hugh Hefner are taking it like a vitamin. And if you want to stay on the edge, you better start doing it too!!! Tough times!
The punchline is quite amusing, although far from original:
V. has to be the greatest invention since sliced bread.