Used just like a high five is used. Encouragement, praise, agreement, etc.
Often used when happy. Most people would use this for day-to-day, less important occasions.
Example 1
Guy 1: "i just made out w/ tht chick 4m history class"
Guy 2: "the blonde 1?"
Guy 1: "ya"
Guy 2: "otihf! u lucky sob!"
Example 2 Girl 1: "hey i ttly aced ms foreys quiz"
Girl 2: "2days test?"
Girl 1: "ya it was ez!"
Girl 2: "i hope i did 2 cuz i studied lots"
Girl 1 & 2: "otihf!!!"
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.