So, do you live a sin-free life? 'Cause if you’re gonna commit the occasional sin and get forgiven for it, I can’t imagine a better choice of sin than masturbation. Not in the shower, though …
It may relate back to Onan, and spilling the seed, Genesis 38.
[QUOTE=wiki]
When Onan had sex with Tamar, he withdrew before climax and “spilled his seed [or semen] on the ground”, since any child born would not legally be considered his heir. He disregarded the principle of a levirate union, so God slew him.
[/QUOTE]
Though later in the article, it doesn’t relate to masturbation so much as twisting it to forbid using birth control
ETA: Linky
It’s been years, the water is lousy lubrication.
Strictly speaking, it’s sexual activity outside of marriage that is verboten, but if you are married you are allowed to get up to whatever hanky-panky you want as long as actual PIV sex is ‘open to the possibility of procreation’. Masturbation, if I remember my classifications correctly, is a violation of the commandment against adultery.
I voted “I’m a guy, zero”. Why? Because I have a very devoted wife…
So long, suckers.
Guy, zero. For some of the above reasons, but mostly because I have a wet room and I’m too stingy to heat it - I get naked for the hot water, dry and dress in front of the fire…and rub one off as a soporific in the warmth and comfort of my bed. Also, 52. Not sure I could do it standing up anymore…
I could have a girl/wife with an ‘S’ cape hanging out of her, indicating her super and frequent sexual activity with me, and I still look forward to taking care of my own business.
But not in the shower.
Between a married couple, other things can go on, just not with the intent of preventing procreation. ETA: What Stickler said! Did not see you there. 
Sadly I don’t live a sin-free life, but I try not to sin on purpose just because God is merciful. My self-abuse tends toward gluttony and pettiness.
Wow, I would have expected a lot more guys to masturbate in the shower. Though physics-wise it makes perfect sense to me why this would be unpreferable. Do guys have a hard time staying on their feet while coming? It seems like that might also be a factor.
I’m 40 and grew up Catholic, going to a Catholic grammar and high school, and it definitely was mentioned, under the euphamistic “self-abuse.” Which, being stupid adolescents, we thought it was the height of humor to smack ourselves in the face and say “look, I’m masturbating!” (or something to that effect.)
As to the OP, very rarely these days. I can’t remember the last time doing this particular activity in the shower or tub. As an adolescent, it was fairly common.
Other than the obvious “hard time” joke…nope. That’s never unbalanced me.
Just the night before last, I got up from bed to take a whiz, got woozy from standing up too suddenly, and fainted, bang, stretched out my length on the floor with a smash. Skinned my knee and elbow.
(First time I’ve had a skinned knee since I was ten!)
Twice now my father has thrown himself out of bed fighting with someone in his dreams. Once, face first and nearly bonked his head on the dresser. He’s been lucky so far.
Woman, voted zero… and not since those dang water saving shower heads came onto the scene years ago.
Jinx. He did it again this afternoon and scuffed up his forehead, split open his nose, and sprained his neck. I say he needs a loose restraint tied around the bed and him.
I (a woman) voted 1-10. It’s a pretty common bath activity. The shower not so much.
I used to, on occasion, when I had roommates (I’m female). But now that I live only with my partner, it’s pretty pointless. When I masturbate, it’s in bed where I’m comfortable. Once, my S/O was asleep and I didn’t want to wake them, so I took a shower, but I selected zero because it just never happens other than that.
I’m curious about the people that chose 20+ - is that your main source of masturbation? Is there a reason you prefer the shower instead of your bed?
Do Catholics actually don’t masturbate? Well, I guess you can’t answer this question for other people, but I would have expected that 99,9% of them do.
I can only report the guidelines, not how well anyone follows them besides me.
Easier to clean up. (Male.) The spooge just swirls down the drain. Also, lubrication (I use soap, and have never had problems such as noted upthread. Maybe that’s my mutant power.)
If I were to do it in bed, I’d need a receptacle. Condom, or old sweatsock, or something. Otherwise, lotta laundry to do.
The problem with doing it in the shower is that I never take a shower specifically to masturbate. When I’m in the shower it’s usually because I’m getting ready to go to work, and I just ain’t got the time nor inclination for the pause that refreshes. The other time I am apt to be in the shower is when my girlfriend and I are getting ready for Business Time, and though hanky-panky might occur there before moving to the big stage, it’s definitely not the time for self rub-a-dub-dub.
Guy, zero. I live alone, so don’t need to hide in the shower 
Also, previous experience with doing it in the shower when I was younger. I discovered that semen turns into a curdled, sticky mess when exposed to hot water.