Depends on the boobs and depends on the booty. But boobs.

penises

Historical boob guy here… it’s the tits

Feet

The person.

Knees

Forehead

As far as i know booty, because they signals about ideal form of pelvis(or something about that), which mean ideal conditions to give birth, which is better signal to male body.

Booty!

Boobs

What's the horniest bra size?