If someone always had a good flexibility,then its possible.The Longer the cock the better.
Inspired by experiences from the past and because of this thread i did it today, i pushed my feet against the wall to suck my cock as deep as possible.
It isn't very relaxing and i couldn't breath very well so i had to make always a few seconds of a break.
Unfortunately i went over the top and pushed to hard .
If you are not one of this incredible circus artist or yoga masters then it's not much fun as many expected.
Not a good replacement for getting a blowjob