Updated

Capitol Hill interns might miss out this summer on a famed lecture from Oklahoma Sen. Tom Coburn on the dangers of sexually transmitted diseases -- all because of a dispute over who will pay for pizza.

The Senate Ethics Committee is requiring that Coburn, a Republican, buy the pizza for the 150 to 300 interns -- rather than have outside groups that have previously helped sponsor the event foot the bill.

Coburn spokesman John Hart said the "safe-sex slide show" -- which Coburn, a practicing obstetrician, has given annually since 1997 -- is on hold pending a decision over who will buy the pie.

"It's something we're going to be discussing," Hart told FOXNews.com.

He said the Senate Ethics Committee has strict rules regarding outside groups, and that it "would argue that that's an outside group increasing our office account inappropriately" -- a rule he said "doesn't make much sense."

Coburn's safe-sex slides, which have often featured graphic images, are meant to "educate interns in the Capitol community about the dangers of sexually transmitted diseases," Hart said.

In past lectures -- including Coburn's famous Star Wars-themed STD presentation  in 2005 -- the senator urged youths to use condoms to prevent the spread of fluid-born diseases like HIV/AIDS and gonorrhea. But Coburn argued that condoms are insufficient protection against many other STDs, including herpes, syphilis, and the human papallomavirus (HPV).  The senator has called on condom manufacturers to issue a "cigarette warning" on boxes, stating that condoms don't protect against many STDs.

Coburn came under scrutiny by the Senate ethics panel in 2005 for planning to having outside groups sponsor the lecture.

"The House Ethics Committee, which enforces a more stringent body of rules concerning outside sponsorship of events, never found fault with the sponsorship of Dr. Coburn's slide show," Hart wrote in a 2005 press release. "The Senate Ethics Committee staff, however, has concluded that Dr. Coburn is the actual sponsor of the event and should therefore be responsible for the costs of the pizza lunch. Dr. Coburn will submit to the staff directive."

Coburn delivered his lecture when he was in the House of Representatives, and outside groups provided the free lunch at the time, Hart said.

The senator also came under fire in July 2008 for continuing to practice obstetrics in his home state of Oklahoma, in violation of Senate rules that suggest his practicing at Muskogee Regional Medical Center was an endorsement of the facility.