I had one of them feckers under a toilet seat rim in Thailand.
I was stopping on the top floor of a hotel with a toilet flushing problem, for most of the day when I flushed, the toilet would fill up, then slowly drain down, at night it seemed much better and acted like a normal toilet.
I took a young lady back there one night, and the days deposits were still sitting in the toilet, and knowing she would want a shower I hurriedly flushed the "bog" sure enough it filled to the rim, good job it did though, as dark red one of those went swirling down the hole.
Imagine a bite in the bollox "ouch" no thanks.