Yeah, yeah, but it isn't too late to take this one on as it only comes into effect after chatzos today. I also don't recommend mentioning this one at the Seder, especially while you're digging into the matzoh ball soup. (What, you keep gebrokhts?!)
Okay, the background: Chometz must be burned before Pesach. However, if one finds chometz during Pesach, even if it was nullified, then as long as it isn't nifsal meachilas kelev one must burn it on Chol HaMoed.
Thus one must conclude that one must burn one's first bowel movement that one has after chatzos today since it will contain chometz and since we know that dogs do eat the stuff when they're really hungry, it isn't nifsal so it must be burned or otherwise disposed of this.
Based on the gemara in Bubbe Mayseh 1C, the minimal way to dispose of this form of chometz is by flushing it, along with any leaves used, down the toilet. However, the Minchas Pinchas notes that since nowadays we used toilet paper instead of leaves (funny how that modern innovation was okay with everyone) we must either flush the paper or burn it.
In addition, one should be careful not to eat any corn for 24 hours prior to that first bowel movement to avoid the chashash of kitniyos.
Based on the teaching of the Shoteh MiChelm, the custom arose in the 18th century to actually have that bowel movement over an open fire instead of relying on flushing it away. His reasoning was that since we burn all other chometz and this material is also, technically chometz, we should treat it the same way. He was also machmir to have that first bowel movement directly into the fire in case any small pieces got lost between the toilet and the burning site (see refernce to corn above) but in a later teshuvah admits he was only zocheh to fulfill the mitzvah once like this as the following year his psychiatrist and plastic surgeon both insisted he be hospitalizaed just before the holiday when he announced he would try the direct approach again.
Instead we nowadays rely on the V'tipol me'al HaChamor to either allow flushing l'hatchilah or carrying the material and throwing it into the fire.
Once again, happy Pesach to everyone out there.