My explaination is in multiple choice joke response -
She's a Vulcan, so is therefore logical and doesn't show any emotions -
A) Just like my last girlfriend - except for the logic bit and the emotional bit
B) It would be like shagging Aaron with breasts
C) Even if you do your 'go to' move in bed, you'll end up killing yourself before even illiciting the smallest sigh
D) She only gets horny every 7 years - so again just like my last girlfriend
E) She won't laugh at your jokes, but on the plus side, she won't laugh at your willy either
F) You can finally do that 'Vulcanized Rubber' joke after you shag her