Whether you know him or not, you have to support his opinion.

You have changed so much that I can hardly recognize you.

It's changed so much, there are some places I don't even recognise.

Tom was so drunk that he didn't even recognize me.

Tom shot his own dog, thinking it was a wolf.

You can't seriously expect that they won't recognize you in that disguise. That lopsided, dime store moustache is a dead giveaway!