Technically, a tomato is a "fruit" only in the botanical sense -- i.e., it's an ovary. (Women have those too, I'm told.)
But when you're talking about eating one (cuisine), it's a "vegetable" just as carrots (roots), lettuce (leaves), celery (stems), and peas (seeds) are.

So if your sex involves eating, then there's nothing fruity about tomatoes being involved. If your sex is somehow scientific and you do it with tomatoes,* you're talking ovaries.


*Come to think of it, didn't they used to call a comely woman a "tomato" back in the '30s and '40s?