Is it vomit or regurgitation?
Does she just lay it down somewhere for you(your hand, leg, on the desk, etc)?
If she's just throwing up and shaking her head(flinging it everywhere, it looks awful and it's gross. I promise.) then it could be a health/behavior thing.
I've heard of birds that get sick and throw up when they're scared/nervous, and even getting car sick!
It sounds more like the former though, she's trying to say "I love you! I brought you food!" It helps to distract her.
Keep foot toys on you when you handle her, and when you see the first signs of her regurgitating, give her a toy to take her attention elsewhere. We don't want her to think you're her mate, after all!
Most likely just hormonal, your U2 Regurgitates food for you as if you were his mate. Cockatoos, especially U2s are known for "Over bonding" and becoming hormonal. If you cuddle/pet your bird a lot then that's probably what's causing it, try not to touch your bird below the neck as this stimulates them. If your bird's diet is high in fat then this can trigger hormonal behavior as well, your bird's diet should consist of formulated pellets, fresh fruits and veggies with occasional nuts and seeds. Another thing you could do is make sure that your bird gets 12 hours of darkness everyday, longer daylight hours indicate that it's breeding season to your bird.
Cockatoos are not known to regurgitate for their mates. They have other social-bonding methods than regurgitation. Has your cockatoo been to a vet recently for blood work and throat and choanal testing?