Thats some heavy shit... Try uh... shitting more often or drinking more fluids. The longer you hold the log, the more dehydrated it becomes, the denser it becomes, the heavier it becomes, and when that somavabitch comes ramming out of yer ass... BAM! water splashes your hiney.
Then again, maybe it is good to freshen up your asshole after a big shit.
I don't think it freshens it up any, I know that I personally pee before taking the shit. So really I'm being splashed by urine. I find that when the shit is short and has farther to drop the likelihood of splashback is greater. It has more time to pick up speed before hitting the water so it hits with more force. I think the solution is to eat more fiber so it all comes out in one long piece.
Take a few squares of toilet paper and lay them on the surface of the water before you 'purge the bilge. This will lessen the affects of splash back via principles of contact-dispersal. This is known as the 'landing strip'
Then again, maybe it is good to freshen up your asshole after a big shit.
;)