More generally speaking TCOI means to get things done or to accomplish something. Also, to get "get the ball moving" or to work at a goal without hesitation. Results are more important than method and desired results are a must.
When it's most important to TCOI or may take even more effort than normal to accomplish a TCOI mission someone might suggest you "Attack!" a TCOI which later evolved into ATACOI. This usage is only recommended for long term TCOI users.
TCOI originated as an acronym but eventually evolved into a word for further implications. "I TCOIed all kinds of things today."