Just dropping by to add my 50cent to y'all's paranoia: the age does matter cause babies have different microbe presence (nothing is sterile, but even pee of a toddler has different smell and bacteria makeup in part because of a whole new diet). I just would not say that it is just as safe as when you were a baby. Perhaps not as dangerous unless you have something extra-dangerous in your gut, but still - there is a lot of bacteria that are harmless while present in adult intestines you are correct to be aware of dangers to your urethra.
I'd suggest testing it out and deciding for yourself if it is an experience worth repeating.