Viagra is the comedic equivalent of being hit in the face with a two-by-four. Some people think it's funny. In certain, very specific, carefully controlled circumstances, it CAN be funny. but for the most part, it's just stupid. it's such obvious humor ("it's a pill that makes old men have boners! haw haw haw!") that unless used carefully and judiciously, it fails.
And it isn't used carefully or judiciously. it seems like every day, there's a viagra joke on The Tonight Show with Jay Leno, or some moron friend of mine sends me a forward containing a supposedly funny joke which turns out to be about viagra ("get it?! it's funny because it's about boners! haw haw haw!"). for example, see viagra lipstick ("get it?! bill clinton had a boner! he used viagra! haw haw haw!").
so please, please, please people. help make the world a funnier place - leave viagra jokes to trained humor professionals.
that means you, Jay Leno.