Here's a few I've heard....

Milksnakes are called that because they are attracted to milk. They will get loose and go after your baby. (these are the same folks who think Fluffy the cat is just waiting to smother your newborn infant the first chance it gets)

Snakes are all the same gender. They don't need another snake to make babies. (please don't tell my male snake Riordan this, he rather fancies himself a stud )

Everyone in your house is going to die of salmonella! (please don't eat at your local fast food joint, you seem to be a bit germ phobic and you really don't want to know what's likely growing on your own kitchen cutting board)

I know somebody who got killed by their pet snake!!!! (when pressed for further information this "somebody" is actually the friend of some guy who may or may not have worked or have gone to school with their third cousin twice removed's ex-wife)