NEW YORK (Reuters) - New York officials were red-faced Friday after discovering clothing ads on city buses appearing to promote reading instead suggested a love of books could be rewarded with oral sex.

The advertisements that ran on about 200 buses across the city in recent months carried posters displaying a suggestively posed woman in hot pants kneeling among a pile of books beside the snappy slogan, "Read Books, Get Brain."

What unhip, unsuspecting local transportation officials did not know was that "get brain" is street slang for oral sex.

The ads -- placed by hip-hop clothing maker Akademiks which intended the double-entendre -- was stripped off New York buses Friday after transportation officials discovered the street slang meaning.

Metropolitan Transit Authority spokesman Tom Kelly condemned the "vulgar street phrases" in the racy ads he said were "demeaning [to] women."

"To me and I believe to everyone else, while it was done by a clothing line, it would give the impression that it was also promoting reading and literacy," Kelly told Reuters.

"It's easy enough to understand how that would get by based upon someone not knowing the expression," he added.

A spokesman for the New York-based clothing maker noted the ad campaign had run since September and "we hadn't had any complaints at all."

New York officials may not be the only ones caught out.

Akademiks also placed the ads on buses and bus shelters in Miami, Chicago, Los Angeles, Detroit, San Francisco and Philadelphia, the company spokesman said.

Kelly, who said he was his 60s, said he ran a test among some young MTA workers after he was tipped to the hidden meaning of the phrase Thursday.

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"I went downstairs to the mailroom and showed some of the young guys a copy of the ad," he said. "I was watching their faces and they all started smirking."

"In music that's how they refer to it," Kelly said. "I didn't know anything about it and I'm sure the people that approved the ad didn't."

The ads followed another recent advertising controversy at the MTA. A poster commissioned to mark the 100th anniversary of the subway was found to contain numerous plugs placed by its designer for the Church of Scientology.