[Les the Scientist (OP)]

I have a friend who swears by viagra regardless of whether he needs it or not.  Now the thing he told me which surprised me, was that you don't get an erection unless you think about one!  I was always under the impression that it happened whether you liked it or not.  So rather than increasing blood flow to a certain nether region, does Viagra also have psychological effects too ?

[ukmicky]

its true. but the problem is once you taken one(not me) how would you forget that you've taken it