There's a fine line between a numerator and denominator.
A photon is going through airport security. The TSA agent asks if he has any luggage. The photon says, "No, I'm traveling light."
A mosquito cried out in great pain,
"A chemist has poisoned my brain!"
And the cause of his sorrow
Was para-dichloro-
Diphenyl-trichloroethane.