Where I found this comic
If you don't get the joke, this involves a play on words of "lactose intolerant" which is when a human or animal cannot digest lactose, the sugar in milk properly. Because lactose sounds like lack-toes and snakes lack toes and many people don't tolerate them, we end up with the lack-toes intolerant, or, in scientist's terms, ophidiophobiacs. Either way, do what it says. Don't pay any attention to the lack-toes intolerant unless you're trying to educate them.
This cartoon copyright 2013 Bob Thaves & Tom Thaves