ASSUMING THIS IS A HEALTHY BIRD WHO IS NOT THROWING UP...(A vet could confirm this..)
You want to make sure you are not a sexual object to your bird, as this is often a sexual behavior (assuming it is regurgitation and not vomiting)...it is a sign of affection, but its a sex thing when they reach a certain age, so you can be secretly honored that your bird likes you A LOT, but DO NOT lead your bird on, and don't encourage it in a younger bird, because it won't be appropriate in the future..
Don't attend to this behavior in any way (no scolding, no commenting etc...you want to act like it didn't happen and change the subject if you think it will happen or if it just did). It's a nice gesture, but not one you can follow through on, so...for your bird's sake (and for yours) make sure you aren't considered a mate in this equation.
1. NO SNUGGLE HUTS/TENTS/ access to shady or dark spaces in or around the cage (including boxes, drawers, low shelves, under clothes, under pillows, under furniture, etc etc).
2. 10-12 hours sleep nightly on a schedule.
3. PET ON HEAD AND NECK ONLY-- anything else is like foreplay and no matter how much the bird likes it, you don't want to take that route because if you can't "do the deed" with your bird, eventually you will be on the "poop" end of the stick...if you get my drift...