They have a cloaca tract, which is their reproductive and excretory tract, and there is a slight difference in the ridges and bumps, the innies and outies.

Large intestine: part of the digestive tract between the small intestine and the cloaca.

What? - Lauren's cloaca is fully engorged! - They're totally doin' it!

When the professor finds out, he'll tear me a new cloaca!

What if he rolls over on his back And his cloaca fills with mucous?