NEW YORK — To some, the idea might seem a little strange: Go to Barneys New York, spend $600 on a new pair of summer sandals and have them graffitied along the sides with magic markers.

But when the shoes are Christian Louboutin’s, and it is the shoe god himself doing the custom artwork, the people will come and the lines will snake around the corner.

“K-U-M-I-K-O,” said a young Japanese woman with a Balenciaga handbag as she directed the designer, who was drawing lots of flowers and hearts along the sole of her shoes.

“Frida,” said the next, who had big hoop earrings, painted white nails and seemed to take her fashion inspiration from Drea de Matteo circa her “Sopranos” run.

“Oh, no,” said the woman directly behind her, annoyed that Frida had decided to buy not one but four pairs of shoes. “I have a plane to catch.”

And she had reason to be worried: Monsieur Louboutin was happy to doodle on as many shoes as a woman’s credit card could possibly handle. “This is nothing,” he said, when asked a few minutes later if he was getting tired. “When I draw, I go for hours.” Marking up his shoes was an idea long in the making, he explained. “I like Pop Art,” he said. “The red sole,” the Louboutin trademark, “came from looking at Andy Warhol’s prints.”

Among the women in the crowd were a Japanese flute instructor named Hae Choi, who bought a pair of espadrilles with polkadots; a blonde opera singer named Suzanne Woods (“under 40, but not by much”) and Liliana Marchena, a 21-year-old senior at Pace University, who wore big Chanel sunglasses and had perfectly ironed black hair.

“Louboutins are very chic,” Marchena said. “I like the chicness.”

When she gets out of school, she said, she’d like to work at Vogue.

And her new patent leather stilettos would be just perfect there. In black magic marker, Louboutin had inscribed them with a sentence that pretty much sums up the life philosophy of young fashion editors everywhere: “Ain’t No High Heel High Enough.”