The Diddy trial is putting his freak-offs on the world stage ... and a famous sex therapist says there are elements from the now-infamous sex marathons that couples can use to spice up their relationships -- and there's a legal way to make it happen too. Dr. Laura Berman, best known for her show on the Oprah Winfrey Network, tells TMZ ... lots of folks are struggling in their sex lives, either from a lack of sex or boring sex, and that's why the freak-off element of the case -- for all its appalling elements -- is also titillating to some.