It's funny, we select our marks by calling them out. This is not a dignified or scientific process at all, rather it is reduced to selective process akin to being in junior high. It could sound like this:
"Hey, what about the smurf at the crosswalk?"
"Hah! (*snicker*) A smurf."
"Nah, too easy."
"Well, how about Mike Tyson heading this way, or Ted Turner sitting at the tables?"
"Let's go with Tyson."
"OK, hee-hee, Tyson."
"Everybody in agreement, we're going with Tyson."
Followed by inconspicuous -- and not so inconspicuous -- stares in that direction.