Why did I get this on firefox?

I adopted a pet from the pound and googled it's name. Only one thing came up. (And it presumably looks like the last pet's lookup) When I clicked the link (and it was neopets.com) I received this weird message from firefox, what does it exactly mean?
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For some reason it's using HTTPS, which is for secure web transactions. If there is no 'certificate', then it is 'untrusted'. Remove the 's' from the HTTPS and you should be fine, the question is how did it get there in the first place *lol*

Oh okay. :P Thanks Zixi.