I haven’t gotten many technical questions. The average person on the street tends to have very little concept of what they’re seeing.
Besides that, show them things you know, and that you know look impressive. If you’re doing it from a Bortle 9 city sidewalk, that’s pretty much the Moon, Jupiter and Saturn, though some other things can be good too. But nevertheless, the list of highlight from-the-city objects isn’t exhaustively long. Accordingly, pick a few that are available in the current season (at around the time you’d be out there) and start studying up on them a little bit.
Example, Saturn: It’s over a billion kilometers away! ("Wow") It’s composed primarily of hydrogen gas along with some helium, while the rings are composed primarily of ice. ("Okay") It has over 100 known moons, though most are just small asteroid-like rocks. ("Well, that’s certainly a lot of…") The one easily seen moon is Titan, which is larger than the planet Mercury and is the only moon with an atmosphere. ("Mercury?") [Okay, you’re already past done — probably lost more than half of the audience already
] A day on Saturn is only about 10 hours long ("Okay, okay"). It’s density is less than that of water. ("Huh?"). The rings of Saturn were first seen in 1609 by Galileo Galilei, although he didn’t perceive them as rings and instead described them as looking like "ears" ("Boo.") The rapid rotation rate of the planet cause it to take the shape of a distinct oblate spheroid ("Mom, let’s get outta here. I’m hungry." "Yeah, this stinks!")
You: "Hey, where’s everybody going?! I didn’t show you Jupiter yet! Come back!!"
The point: You don’t have to be Encyclopedia Brown out there, though you don’t want to look completely clueless. A few fun facts is generally plenty, and often not even needed at all. Typical: "See that star up there?" Yeah. "It’s actually a planet. Have a look at it through the eyepiece here." Really? "Yeah, have a look. Don’t touch, just look." I don’t see anything. (you re-check) "It’s there, look again." (person looks again; jaw slowly drops) Ohhh. "That’s Saturn. The planet Saturn" OMG. Is it real?, it can’t be real! (looks again) Honey, come here, you have to see this. Wow! Thank you, thank you.
That’s pretty much it. Most people hurry off to go look up Saturn and try to figure out what it is they just saw. A few don’t care much — it’s just too abstract. A few want to talk about their cool hobby. Some want to share with you how they love space or science fiction, or want to get a little philosophical about other life out there or about the future. How much does the telescope cost? Can you see the flag on the Moon? Stuff like that