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1.
When you have a poo, you feel it come out, but when you go to flush the toilet, (and of course examine your "modern art") there's no shit there!
Woah, so freaky. I just had a phantom poo!
by cool_penguin_0 February 06, 2005
 
2.
A poo that hides behind the U bend of the toilet, therefore leaving only its phantom essence.
As I stared down in bewilderment down my empty toilet, the thought occured to me that I must have had a phantom poo.
by Jasta111 June 05, 2007
 
3.
When needing the toilet for an extended period of time and finally making it to the bathroom, you complete your business only to find that nothing actually came out even though it felt like you pushed something out.
Mark - "Hey John, just went to the toilet and I thought I did a massive Shit, I turned around and looked in the bowl and there was nothig there!"

John - "My friend you just did a phantom poo"
by pokey_puppy April 17, 2011
 
4.
When you do a terd and go to wipe your ass and theres no poo on your anus
"where did that shit go,must have been a Phantom poo
by Phantom Poo Man August 29, 2006