Men…

[Watchyoupee 234]

Have you ever rubbed your head just around your urethra until you involuntarily pissed? It feels really good. Almost like cumming. 
I can piss in the toilet or shower and drain my bladder all the way and then rub my tip and shoot out more warm piss into my hand. I can usually do 2 or 3 in a row before it gets too sensitive. 
try it out. 

I usually use lube or soap in the shower and join my index and middle fingers together pointing down and rub my tip up and down the length of my two fingers repeatedly and quickly it usually doesn’t take long before it feels good and you stay spraying. 
Let me know how it goes. 

[Watchyoupee 234]

Also a jet or warm shower water on my head will cause an involuntary piss as well.

[Pooler 191]

If you do that to me it will make me cum. For me, rubbing the back of the head (opposite the urethra) with no other stimulation will make me involuntarily pee.  I guess everyone is different.