I have to concur with Shifty and Cunning. Statistically the average is 5" to 6", so people are definitely adding an inch or two, despite the anonymity of the poll.
Now me, my cock is so big, I scare myself.
Last time I got an erection, it tore a hole in the space/time continuum. Luckily, my cock was big enough to plug the hole, and I shot a load of semen that filled the alternate universe.
Yes, I drowned and entire alternate universe in semen.