When I was younger I had this shower head that I could adjust to a single hard stream. I'd let that hard stream hit my cock-head and cum-off like that with just the stream hitting my swollen cock-head. It was a little hard keeping the stream on my cock-head once I started cuming and my cock started twitching around but once I started cuming it didn't matter because I wasn't going to stop cuming then. It just turned into a hands-free cum shot.
Although I use a shower head quite often myself.