The problem with a lot of Viagra ads is that they don't just come out and say what it's for in a quick and catchy way. So how about this: "Viagra: The Quicker Dicker-Upper."
(This is obviously a play on the Bounty paper towels slogan: "The Quicker Picker-Upper.")
(I know I have posted this joke slogan before a couple years back, but I can't find it, as I tend to overwrite everything on this blog, so I'm putting this thing up again, so to speak.)
Oh, and the real slogan (as opposed to the joke slogan) they should use is: "Viagra: Rise to the Occasion!" (Has anyone used that before? I haven't seen it; although I must admit I am not an expert on boner-pill advertising slogans.)