I just got a probing kit and decided to try it out on a known male first, (he's nearly 2 and he likes to flash his junk at me, that's how I knew he was male) So as I probed him and no worries, I've found it's quite easy and watched my vet do it, well, while the probe was still in, he popped his other peen out just to prove a point I guess... Cute? :/