Meant to be used sarcastically when a person spontaneously tells you something you do not need to and/or want to know.
You: "TFI!" or "Thanks for the info!" (with a sarcastically surprised look)
Too Freakin' Intimate.
Too F'n Intimate.
Or someone opens a bag of chips and is sharing it and one of the others double dips and/or stick his hand in the bag to get more chips after licking his fingers.
Or A person talks about their bathroom habits or their underwear preference with coworkers.
Or A coworker calls another coworker from the bathroom or bathtub.