Check The Internet
An acronym used in a few situations as a quick way to either make up for your own lack of knowledge or as a sarcastic comeback when being questioned on something that should be common knowledge.
It is also used as a way to point out something obscure when posting on forums that you know no one would get right off the top of their heads.
The backing for its use is obvious, the internet knows all.
Guy 1: Hey, what does CTI mean?
Guy 2: CTI
I also consider K-ON ( CTI ) to be a superb anime.
call / text / im
girl: bored cti