No Ifs, Ands or Butts

good morning, herr doktor.
ah, there you are, my boy. just in time to help with my demonstration.
of what?
how proctologists can minimize the chance that their colonoscopy patients will suddenly explode!
what?
now pull down your pants and bend over.
doktor! what is that thing? it's. . . huge!
this, er. . . probe? mein gott! it's quite heavy. but don't worry! you'll hardly feel the pain. eventually.
but. . . !
butt is right! (hmmm. that reminds me: I'll soon need another assistant.)
you will?
to clean up the mess, of course! the things we do for science!