Insert an 18fr catheter (from AliExpress) until pee starts to come out, then instead of inserting it all the way, I slowly inflate it inside my sphincter until it starts to hurt & hold it for at least half an hour before deflating the balloon & removing the catheter.
there is a high risk of a UTI & possibly even permanent damage, so I don’t recommend copying my risky behaviour.
also, I seem to be less sensitive than others - I have heard insertion and removal of catheters is painful, but that has not been my experience. If normal use of a catheter is painful for you, my method is an even worse idea.