1. when you've had a crap and wipe your arse but the sheet comes back clean, and you wonder if you actually went.
2. a phrase meaning you've had good luck
1. "I was running late but I really needed a shit - luckily it was a phantom, so I made it to work bang on time."
2. A - "Hey, you look happy."
B - "Yeah, I've been having phantom shits all week."