never do it. I know someone who had diverticulitis and holding it too long, blew a hole in his colon that was situated next to his bladder so blew a hole into that also. he wound up with a fistula between the too which meant he had communication between his colon and his bladder. not good. got peritonitis that led to sepsis.
Well, I like to hold them in, especially if I know I'm going to be around people. In a store, I'll let the relief valve go and usually a woman or old Lady will say, "Well I never", to which I reply, "You ought to, you'd feel a lot better". lol