Oh Giardia! (upon seeing a beaver shitting in the river upstream from you)
Friend: I've got a bad case of the shits man.
And then the cows poo in the Green River, and then your canoe tips, and you aren't expecting it, and you swallow cow feces water and ten days later you get the bloody fuckin' shits.
And you have to go buy Pepto Bismal.
But you still have the bloody shits.
Because Giardia is nasty and Pepto doesn't help.
"Oh so that's why you haven't been at school." said Steve the math teacher.
"Yup, I got the bloody shits."