An abbreviation of the word 自己中心的 (Jiko Chuushin-teki) which means selfish, egocentric, or self-centered
自己チュー(Jikochuu) means that someone thinks he/she is pretty much the most important person in the world and he/she couldn’t care less about doing things for other people.
This phrase doesn’t really have a positive meaning and is often used casually with friends, family, or those close to you. In more formal situations, the words わがまま(Wagamama) or 自分勝手(Jibun Katte) should be used rather than 自己チュー(Jikochuu).
Example (two female friends are talking amongst each other)
A：Ugh, my husband is the most selfish jerk in the world!
B：Whoa girl, what happened?
A：I was just watching TV minding my own business when he comes over, doesn’t say anything, and changes the channel on me!
B：Oh, you’re right. He is the most selfish jerk in the world!