Five inches is not enough
The probability is high that you have read this phrase as a subject line of one of the many "penis enlargement spam" mails that are currently flooding the net.
It is interesting, though, what kind of association I initially had (and still have) when first reading that phrase in my inbox: High heels.... where I actually think that five inches are enough, but well, sometimes they aren't, if you want to torture your victims feet a bit more ;)