Don Imus is being sued for more than $4 million by an advertiser on his former show who says the radio shock jock badmouthed the company and called its commercials for a book by the late President Gerald Ford "cheesy."

Flatsigned Press Inc., a book publisher based in Nashville, Tenn., says Imus insulted the company last year in ads it paid for to promote a book by Ford on the Warren Commission's investigation into the 1963 assassination of President John F. Kennedy.

On his "Imus in the Morning" show, the talker told WFAN listeners the publishers "have been waiting for (Ford) to croak so they can unload these (books)," the lawsuit claims.

Besides calling the ad spots "cheesy," Imus said of Ford's death, "Now that he's flatLINED, you go to flatSIGNED.com," the lawsuit filed in Manhattan's state Supreme Court says.

Marc Held, Flatsigned's lawyer, said Thursday that Ford approved the book and signed the copies Flatsigned was selling. Imus was told to read the script "word for word" and not insult the sponsor, "but he kept doing it," Held said.

Flatsigned's sales dropped $40,000 a day for several months after Imus' "libelous and disparaging statements," court papers say. The papers also say stores refused to stock the book because of his comments.

Flatsigned said it paid for two 30-second ad scripts a day for three days — Jan. 29, 30 and 31, 2007.

Imus, 67, read the first script as written, court papers say, but in later readings of the script, he made "unequivocally unacceptable" remarks about the publisher, even after officials at CBS, WFAN's parent, asked him to stop.

Karen Mateo, spokeswoman for CBS, said she had no comment on the lawsuit.

Imus, fired from WFAN last year after making a racially charged remark about the Rutgers University women's basketball team, now has a syndicated show on New York's WABC, which is owned by Citadel Broadcasting Corp.

A spokeswoman for Imus did not immediately return a call for comment, and his lawyer, Martin Garbus, was said to be traveling.

At a point where Imus was supposed to say Ford hand-signed the books before he died, Imus asked, "How else would he sign them, with his foot?" the lawsuit says.

During another ad spot, court papers say, Imus said, "Now that ol' President Ford has flatLINED, buy your piece of American history at FlatSIGNED.com."

Court papers say Imus acknowledged, "They asked me not to say that, but ..." He then agreed with someone in the studio that the play on words was too tempting to pass up, the lawsuit says.

Court papers say Flatsigned rejected an offer by CBS and WFAN in February 2007 to provide 15 "make good" commercial spots on other programs.

The lawsuit asks for $4 million in compensatory damages for breach of contract, libel and malice, and for another $59,000 spent for a newspaper ad that ran after the commercials on Imus's show.