The best kind, well, next to bathroom humor, which Family Guy has covered.
I was studying at my desk and saw a bat-sized mosquito hanging out on the wall. Being practiced by this point, I grabbed the nearest object that I could to swat it...
thus grinding a mosquito corpse and a pretty significant blood spatter that I presume came from me, directly into the cover of the "Pathologic Basis for Disease".
I swear, I'm just going to rip the cover off and turn it in as my next concept map.