The phrase "to catch the poop" means to take responsibility or to catch someone doing something wrong or making a mistake.
Sentences with «to catch the poop»
In general, the only time they get a diaper rash is if we eat a lot of citrus or tomatoes and then don't catch a poop quickly enough. (natural-parenting-advice.com)
Fleece liners wick away wetness from baby's skin and also catch the poop for easy deposit into the toilet. (themamaknows.com)
And I actually caught a poop this morning by intercepting him as he was pooping in a corner! (godiaperfree.com)