Weird question, but I just want to make sure the icky stuff I found is poo.

Well, you'll have two types of excrement. A white chalky substance (urates) and the actual "poo" which depending on the snake can look different, but along the lines of dog poop.
Describe what you mean by "icky" it could be a regurge, or it could mean sometype of underlying problem with the snake.

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"Nobody can do Everything, but Everybody can do Something."

It smells bad, is lightish brown and glossy some. I was in a clump and I was afraid it could be throw up if poo was individual droppings and not a pile.

It is a cali-king if that helps any.

It's not really clear from your description what it was. When did the snake last eat? What color was the last food item? Did the icky stuff look like a half digested mouse? (with hair and feet, etc.) If the mouse was white, you're probably looking at stool. If the snake ate less than a few days ago, it could be a regurge or vomit.
If it was a regurge it would REALLY REALLY REALLY stink like rotting vomit (or worse.)
Urates and stool smell fairly bad too, but not as bad as a regurge.
For the record, urates look a bit like bird droppings white with yellow and a mix of fluid and chalky substance that can clump and harden.
Stool looks like what a dog or cat would leave behind.

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Andrea

Urate sounds like it then BJ. It did stink, but the colors were what worried me. I guess white chalky and yellowish describe it well. After all this info I think urates have to be it.