Rich Rodriguez to Accuser: I Didn't Show You My Penis, And I Got Proof!

Rich Rodriguez is firing back at his ex-assistant accusing him of sexual harassment -- saying her claim he grabbed his wiener in front of her is such complete bullcrap, he took a lie detector test to prove it.

It's all outlined in RichRod's attorneys' response to Melissa Wilhelmsen's notice of claim filed with the AZ Attorney General's office ... where they denounce the allegations that the ex-University of Arizona football coach terrorized her for years.

In the 290-page document, Rodriguez's lawyers poke holes in Melissa's most serious accusations -- including the "shameless, outrageous lie" that RichRod began "grasping his penis beneath his basketball shorts" in a closed-door meeting.

His lawyers say Rodriguez took a "rigorous polygraph examination" administered by a member of the American Polygraph Association to fight this claim -- and the results prove their client's innocence.

"The relevant questions put to him were, 'Did you ever expose your genitals to Melissa?' and 'Did you ever show your genitals to Melissa?' Coach Rodriguez answered 'no' to both questions."

"The testing confirmed 'no deception indicated' ... this event simply did not happen."

Of course, the accuracy of polygraph tests are controversial to say the least. Most courts won't allow polygraph results to be submitted as evidence in a case.

In the new filing, Rich's attorneys also slam Melissa for claiming RichRod ignored a warning from a team staffer about his former player, Zach Hemmila, the day before he committed suicide.

"Of all the Wilhemsens' false claims, there is none more cruel and despicable than this one -- attempting to use the tragic accidental death of a young student-athlete to extort $7.5 million from the Rodriguezes."

They claim Rodriguez actually spoke at length with Zach in the days prior to his death ... and had also been in contact with his family.