Usually we picture crap coming out of Lindsay Lohan's mouth and not necessarily anywhere else. Because everyone knows girls don't poop, duh.

But we were forced to ponder such unpleasantness after a report surfaced accusing her of stopping up every single toilet on the set of 'Scary Movie 5' -- something that, according to her, was totally not her fault.

Then again, what is?

TMZ reports that Lohan is pissed (so to speak) and thinks she's being framed for the plumbing mishap, claiming that producers were peeved at her for missing the first day of shooting for her cameo with Charlie Sheen.

Why the no-show? La Lohan claims she had walking pneumonia and that her docs warned her not to fly. If only she was that concerned about her health all the time.

In any case, Lohan claims that the trailer, its shower and its toilet were trashed when she finally arrived a day late, forcing her to do her showering and other hygienic tasks in neighboring trailers.

She swears she was never told she was being charged for the plumbing issues until after shooting, and insists she went back and forth with the film's producers about the drama for weeks.

Lilo finally gave in to get them off of her befreckled back, at which point they deducted tens of thousands of dollars from her paycheck -- every cent of which she needs -- to cover repair costs.

Our advice? Get a plunger. And know that a toilet is no place to dispose of a dimebag.