That's kind of cute, and considerate of your BP
I have never seen my ball poop... in all the months I've had him, his presents have been burried time and time again. However, I have had MANY encounters of the turd-kind with my corn snake. She doesn't wag her tail as such, but sticks it straight out sometimes. If I massage her it almost always gets her to poop on command. Because she is a thin species of snake I can see her muscles contracting right before it happens, too. A little warning is better than no warning!