An adult that is selfish, irritable and naive like a child.
- How was your Valentine's Day?
- Well ... There was a tantrum, popcorn and a bear movie. I realized that s/he is an Hello Kiddy Person.
A guy who ignores a girl's texts and instead replies "hi" two days later as if nothing happened.
(text messages)
A: where do you wanna meet up later?
B: (two days later)
Hi!!!!!!!!
A: omg, stop being a hello kiddy!!