i lifted this from another site several years ago. can't remember the author; don't think anybody will ever beat it.

"Back in July this year. Too much to drink the night before, and bad
food. I'm driving from Weekapaug headed to Quonny. I get to the light
and the gut starts talking to me REAL LOUD. Now I'm debating...go
straight and hit the Mobil or take the right and hit the potta-potties
( if any of you listen to Howie Carr you know the reference )I go
right. About 10 seconds down the road my A-hole is screaming at me,
should of gone straight. There are about 5 vehicles behind me. I'm
sweatin it as my butt hole is clenched as tight as possible but the
fist in my stomach is doin' its damndest to push out the foul mixture.
I look in the back of the van. I don't have a googan bucket ( bad,
very bad ) no where to pull over and dump. I look back again and see
my eel cooler ( soft six pack cooler ) of course it has a 1/2 dz. eels
in it w/ ice. next to the cot. Decision is now be'in made for me.
Thank God I didn't have my neo's on. I practically power slide over to
the side of the road and bail into the back. Drop trough as I am
unzipping the cooler. Of course I forgot to slam it into park so the
van starts moving the same time as my bowels. I just reached over and
bang it into neutral for the time being " Ka Thunk " ( no, not my A
hole the tranny ). I grab hold of the cooler and don't even get to a
squat and projectile crapping has commenced. Well let's just say the
eels became pretty active suddenly and that cooler was filling up too
quick. I look out the back of the van windows and who's sitting there?
Yep, Charlestowns finest. He walks up to the drivers window and the
smell must have been the trigger. I'm looking through the side window
at him and he probably can only see my siloutte ( tinted ). He asks "
is everything OKAY in there? I'm sh!ttin my pants both ways. I reply I
needed a sudden restroom break and that currently the back of my van
is Rhode Islands newest Porta Potty. He kinda chuckles and walks over
to the side where the sliding door is. I crack the sliding door and he
pulls it back about a foot and looks in. Now he can see the cooler.

The eels are squirming around in the plastic bag under this pile of
... and his eyes are like... OH MY GOD. He turns around gagging. Now
I'm laughing and crapping at the same time. He walked back to his
patrol car and pulled away. I kid you not. He must have thought I just
gave birth to the spawn of Satan. I grabbed a roll of TP I always have
in the van and proceed to finish up. That was one of the best Sh!ts I
have ever had regarding relief. I laughed quite a bit on my way to
Quonny thinking... what would the ticket have been for?"