Not sure why you're claiming it's yours. It's a popular advertising slogan, combined with a popular template. It would surprise me if someone hadn't done something similar before yours, as well.
Also, even if he take it, wouldn't you be happy about that? You liked the joke enough to post it, and now a joke you like is on the front page, where more people can see it and enjoy it. No harm in that at all.
I do like the germ bottle you put in, though - that's a nice touch.