Here’s something we could go our entire lives without seeing — The David Letterman Sex Tape. We’re still recovering from the one with Mini-Me.

Better break out the Brain Bleach, ‘Crunchers, because we hear the scandal-plagued talk-show host has been rocked by yet another tawdry bombshell – reports of a sex tape showing him doing the mattress mambo with a “much younger” female staff member.

“Dave apparently didn’t know the location of the security cameras at his Late Show studio.”

Late Show snoops tell The National Enquirer, studio surveillance tape caught the 62-year-old comic in a series of — er — “compromising positions” — with a petite twentysomething he met as a staffer. Unfortunately for The Davester, the X-rated flick could play a key role in the trial of the 48 Hours producer accused of blackmailing him.

“If the tape makes its way into the criminal case, it’ll explode his marriage to smithereens,” blabs an insider. “It’s one thing for him to have publicly admitted to having had sexual relations with some women on his staff. It’s another to see him in the throes of passion with one of those women.”