Check this out.  I just got kicked out of the house my girlfriend
rents a room in, permanently, because her landlord believes that I
actually *spit* in his cat's food dish.  He made her go downstairs and
examine it to verify that it looked human.  He came to his own
conclusion that it could not have possibly come from a feline animal.
I personally did not see the evidence.  I'm not even convinced he
didn't do it himself, but at any rate...

This is kinda gross, but I'm quite curious.  My girlfriend tells me
that it was clear, kinda bubbly, and viscous.  They have two cats in
this house... one is less than a year old, the other is really old,
definitely on his last legs.  My question is:  is there any possible
way this substance could have come from either cat?  They seem to be
in pretty good health, as far as I could tell.