Either talk to him in person or send him another email, and ask him how he feels about the situation.
Ten: While it's nice to have a grasp of current events and knowledge of local culture, it's no longer a first-date pre-requisite.
Be prepared to be judged by all the members of the orgy.
Nine: If you've met the guy online and have never met in person, and if his entire chat so far has been about how amazingly hot you are and how amazingly much he's into you and how he's quite certain you're the guy for him, he will hate you within 20 minutes of your date and you will never hear from him again.
If you're not a good match (and dates are like new restaurants; about one in eight survive), you're both going to share that awkward moment of "Do I un-friend him or keep reading about his 'Why do I always meet losers? Four: Even though gay men love to label everyone, they despise being labeled.
So whether he's a Bear, Twink, Twunk, Cub, Daddy, Dilf, Otter, Chub, Gym Rat, Gym Bunny, or any of the other zillion names we give one another, only address him in generic terms, like handsome, sexy, hung.