A woman has come up from the audience in the back room at Pops Highwood and is standing on the stage with Ross "He Knows What You're Thinking" Johnson. The woman, apparently chosen at random, is silent, concentrating. Johnson, who says he's been "voted the top psychic entertainer in the world" by his peers, has asked her to focus on her best friend's telephone number. In her mind's eye, she's punching it into a dial pad, one digit at a time. Johnson is receiving. He calls the numbers out as they come to him--struggling for a moment, wavering when the impulse seems to weaken, and then, in a burst of clarity, getting them all right. The audience--believers and cynics alike--is wowed. In the last hour or so, he's told some of them the month of their birth, others what kind of work they do. He's guessed the secret messages they wrote on strips of paper and sealed in envelopes. He's identified the woman who's heading to Colorado hoping to meet a new man, and the one who's worried about the person her son is dating. We know there's a trick to this, but damned if we can figure out what it is. Johnson's show, . . . A Funny Thing Happened Tomorrow, opened February 1 and continues tonight (March 8) and March 15 at 8:15 at Pops Highwood, 214 Green Bay Road in Highwood. The cover charge is $19 and seating begins at 7:30; call 847-266-1313 for reservations.