It is possible and not that much difficult. You have to be horny as extremely as possible. That extremely over excitement leads your dick to shoot your loads without touching your dick. I've experienced this so many times. It's happens more quickly if the main object to being over excited and horny is your wife.
I cum regularly without touching my penis at all. I can do it many times in less than 5 minutes just by clinching on my butt plug. My record is 32 seconds. I know because I stopped the porn video when I came and it was 32 seconds in. I was riding this guy:
Use someone else's hands:
I needed one hand to catch it all ...
No hands needed